HVAC system control & switch Questions & Answers:

This article series explains where to find and how to use the switches and controls for air conditioning and heat pump systems.

Air Conditioner Switch & Control FAQs

These questions and answers abour air conditioner and heat pump controls and switches were posted originally

at CONTROLS & SWITCHES, A/C - HEAT PUMP where you will find a discussion of thermostats, zone dampers, and circuit breakers on air conditioners and heat pump systems.

Air conditioning and heat pump diagnostic procedures are at DIAGNOSTIC GUIDE A/C or HEAT PUMP

Chattering relay and air conditioning or heat pump start up problems.

I have an old RUUD heat pump/central A/C manufactured in 86', so there are no circuit boards in the electronics area of the air handler. I recently replaced the blower motor and capacitor, as well as thoroughly cleaning everything.

When I run the system in just fan mode (no heat) it runs perfect.

When I run the system in "emergency heat" it runs perfectly. But when I run the system in regular heat mode, there is a clicking noise I hear from inside of the electrical are of the air handler.

So every time it calls for heat from the outside condenser, there is a constant clicking noise from the inside air handler. Could this be some sort of relay switch or something? On 2024-01-25 by Rich

by InspectApedia Publisher - Diagnose a constant clicking noise from the inside air handler

@Rich,

That clicking sounds to me as if a relay in your air handler is not working.

A question is does the outdoor compressor condenser unit start to run when you call for heat?

There's also a reversing valve that switches the direction of flow of refrigerant in the system that could be sticking but I would expect that you would hear that and the outdoor unit not the indoor unit.

Look inside the air handler and on the back of the door covering the blower compartment to see if you can find a wiring diagram and you should be able to identify any relays and from that you may be able to track down which one is either not pulling in or is pulling in but whatever is trying to start, such as the compressor condenser unit, isn't starting.

by Rich

@InspectApedia Publisher, Yes, the outside compressor condenser does start to run but whatever is inside the air handler that sends the signal for the outside compressor condenser to turn on is clicking on and off rapidly.

The lights in my basement even flicker when this is happening so I don't allow it to run like that for more than a few seconds because I don't want to damage anything.

What is the electrical part that controls the outside compressor condenser on these older systems? Again, no circuit boards in the electrical area above the blower. Thanks so much for your insight.

I really appreciate it as I can't find anything else online regarding this issue.

Sorry, I know you said the relay is what controls the outside unit to turn on. I was just wondering if there is a specific name for it. Thank you.

by InspectApedia Publisher - several relays, also called "contactors" - identified on the wiring diagrams

@Rich,

There will be several relays, also called "contactors" - identified on the wiring diagrams for the indoor air handler and the outdoor compressor condenser unit.

One may, for example, turn on the compressor motor, another the fan.

by Rich

@InspectApedia Publisher, Okay, yes... That's what I was wanting to know. This past summer, I replaced the contactor on my outside condenser, along with the capacitor and relay switch.

I didn't realize that there is contactor(s) on the inside air handler unit. I will take a look at the schematic on the inside panel as you had suggested and try to narrow down the problem. Hopefully get a part number and place an order.

I will let you know how I make out.

Thanks again for the information. You have been extremely helpful.

by Rich - Could it be that the reversing valve was stuck

@InspectApedia Publisher, Okay, so last night I set my thermostat to the A/C mode and powered it on, essentially moving the reversing valve inside of the condenser. I ran that for a few minutes then shut it down.

After that, I switched the thermostat back to heat mode and turned it on and there was no clicking noise at all coming from the air handler.

Could it be that the reversing valve was stuck, possibly? I'm keeping my eye on it because I'm not convinced that this was the actual fix but hoping that maybe that was the problem.

by InspectApedia Publisher

@Rich,

Yes that's certainly possible.

by Rich - A/C ystem now working OK

@InspectApedia Publisher, Just wanted to report back that everything is still running good with no chatter in the air handler

. The system has probably cycled on and off, in regular heat mode, about 25 times now and, thankfully, no more noise.

by InspectApedia Publisher - chattering relay and air conditioning or heat pump start up problems.

@Rich,

That's good news, and thank you for taking time to provide feedback as that will help other readers also facing chattering relay and air conditioning or heat pump start up problems.

I wouldn't assume however that a future repair isn't going to be needed. I have found often with mechanical equipment that a marginal control or relay or device can be got going again but when we leave the equipment off for a time we are back where we started.

How do I turn A/C back on?

Accidently touched a switch that I thought was hallway switch and instantly shut off A/C. How do I turn A/C back on? On 2023-06-18 by Anonymous -

by InspectApedia Publisher

@Anonymous,
Wait 45 minutes, then simply turn the power switch back on and it should work normally

Some A/C compressor/condenser units won't run immediately after turning power off because the compressor can't start against high head pressure that develops during normal operation

A pressure sensor may be present that prevents restart at high refrigerant pressures.

By waiting a bit, refrigerant pressures in the system will equalize and fall to a much lower pressure.

Then the compressor will restart.

Let me know if that works for you..

 

Where's the red reset button on Lennox HVAC units?

Where would the red reset button be located on the Lennox units? inside or outside On 2011-06-03 by juan bowers

Where's the reset button on a Coleman outside A/C unit?

Where is the reset button on a Coleman Outside A/C unit? On 2011-06-04 by Sabrina

by (mod) -

Juan: The red reset button on electric motors, Lennox and otherwise, is described in ELECTRIC MOTOR OVERLOAD RESET SWITCH - see our list of article links in the master index at the end of this article.

Typically an electric motor thermal overload reset button is built into the motor itself and is found on the surface of the motor. You'll see photos of what this button looks like in the article I've referenced.

by (mod) -

Sabrina: there may be no reset button for your outside compressor/condenser unit if it's the compressor motor that is not running.

The fan motor MIGHT have a reset button on the fan motor as we describe

in ELECTRIC MOTOR OVERLOAD RESET 

Try turning the system off for an hour and then turning everything back on.

 

Thermostats wouldn't turn on the heat

I have tried 3 smart thermostats. Each one correctly installed and wired. The thermostats worked well except none would turn on the heat. I live in an apartment. It is heated and cooled with a heatpump.

I suspect that the original installed thermostat, a manual Braeburn 2020NC is the only one which can be installed to run this heat pump.. Could I be correct in this assumption? On 2023-01-12 by Bob Howell

Reply by InspectApedia Publisher -

@Bob Howell,

Gee I'm surprised. The thermostat is in essence just an "on-off" switch that connects the two T T wires together at the thermostat on a call for heat.

PROVIDED that we're talking about a standard 24VAC thermostat circuit (that is, not electric heat or some other system that has to switch a 120VAC or 240VAC relay),

I'd do this test:

Remove the thermostat from the wall and try just jumping the two wires together (red and white usually).

If the heat starts then we know the TT wires and connections at the other end are correct and we can go back to investigating the thermostat itself and its settings.

Should I be running my air conditioner in "exhaust" or in "fresh air" mode

Air control: wiich is right: fresh or exhaust? On 2021-07-16 by Anonymous

Reply by inspectapedia.com.moderator -

@Anonymous,

There is no "right or wrong" answer that fits all cases of the question of "should I be running my air conditioner in "exhaust" or in "fresh air" mode.

Use exhaust to reduce indoor odors

Use fresh air to improve indoor air quality and to dilute indoor air that has odors.

Condenser unit motor runs at half speed and trips breaker

Condenser motor runs half speed then tripped mind u this is a new motor had 2 - On 2021-05-08 by Roy

Reply by danjoefriedman (mod)

@Roy,

It is distressing to keep replacing the motor without finding out the underlying cause that seems to be killing them.

There could be a different problem such as low voltage to the compressor motor or a miscalculation of the refrigerant charge causing liquid refrigerant to damage the compressor motor.

Or of course it's something else.

So if you have to replace this motor to I would talk to the service manager at your HV AC Service Company and ask him to send out an experienced diagnostician to see if there's an underlying problem that should be corrected.

Why is my heat, or backup heat, turning on when we're in cooling mode?

What would cause an A/c unit when in cooling mode and operating to also turn on the heater in air handler? On 2019-08-01 by Bill

by (mod) -

Bill

Thanks for what is a surprisingly common question: Why is my heat, or backup heat, turning on when we're in cooling mode?

I speculate that

- you're describing a conventional A/C system that uses the heating furnace air handler blower unit and common ductwork for both heating and cooling; in cooling mode if the system turns on heat and the thermostat was correctly wired in the first place, I suspect shorted thermostat wires or a bad control board or relay

Or

- you're describing a heat pump system that uses electric backup heaters for very cold weather when the heat pump can't suffice.

In cooling mode if heat turns on it's a similar cause as the first case.

Diagnose why the outdoor compressor does not work but the cooling fan does.

Continuation: I'm trying to confirm that I have a bad compressor before I have a new unit installed. Can you think of any other tests I should perform?

Compressor does not work. Cooling fan does. 11 yrs old. Had to replace Dual Capacitor 3 mo. ago. System is full. Contact relay passes open/closed ohms test and has 120V through it, to compressor, when power is supplied and thermostat on. Circuit board has slow flashing green/red lamps.

Voltage at DC remains 120 for compressor, while fan wire does not. On 2019-06-23 by Tim

by (mod) -

If you take a look in the ARTICLE INDEX at Compressor unit Diagnostics and compressor unit failures you will see the common tests used by technicians. Center around measuring the current draw but there are other side observations that are helpful and of course you want to rule out obvious things like a bad relay.

by Tim

Installed a hard start. compressor started and knocked like bad engine rod. amp draw was 24...max is 14. had a complete new system installed.

Thanks for the response. apparently in the South, 10 years is about the max life on a compressor.

by (mod) - experience with adding a replacement hard-start capacitor.

Tim thanks for the helpful details on your experience with adding a replacement hard-start capacitor.

Indeed techs try installing a new capacitor since that's so inexpensive; but often the underlying problem is a failing motor. That high amps draw confirmed your situation quickly.

A/C & Heat Controls: I'm paying for both my and my neighbor's Utility Costs?

Hi there. I currently rent office space from a landlord who pays the AC/heat (electric bill) each month in his name and then has me reimburse him.

Our AC broke last week and we had to close the office until it was repaired.

At that time I noticed the AC in the empty set of offices (left unlocked and open all the time) on the other side of the wall from my offices was off too.

Then when our AC went back on, so did the AC in the vacant set of offices next door. I went on in again and what do you know?

There is no thermostat anywhere in that empty space. So I am now wondering if I am paying to cool and heat not only my rental spaces, but a set of empty spaces I don't rent as well. The LL is sort of shady so I am pretty sure I know the answer already.

But how can I tell for sure? I called the electric company and they said they couldn't tell how big a space I pay for by the bill alone. If I locate the breaker box is there something in there that would tell me if I am paying for both spaces? Thank you for any help! On 2018-07-02 by Chris Jeffrey

by (mod) -

Chris

here's an easy test:

Next time your AC is running, go into the empty space - notice that it's AC is running.

Then go into your space and turn your AC OFF by turning the thermostat up to way above the present room temp.

OR turn off power to your AC system.

Does the neighboring space air handler also stop?

If so there could be a wiring error or indeed a shared thermostat for the two spaces - as can happen in an older building when tenants and partition walls move around.

Replace the entire heating and A/C system because a switch to the compressor is "stuck"?

Have an American heritage 12 heat and air unit have had repairman out three times now they say the switch from the heat pump to the compressor is stuck they will have to replace the entire unit for 15000.00.On 2017-06-23 by James

by (mod) - Really?

Ask for more details before paying for further repairs. One would not replace a whole air conditioning or heat pump system simply because a control switch is bad and needs replacement.

But IF the switch, by being stuck, caused costly damage to the compressor/condenser unit then that could lead to a more costly replacement.

Even that doesn't explain a claim that both the outdoor compressor/condenser unit and the indoor air handler unit need to be replaced.

There has to be (and there might be) further justification for such a costly repair.

Diagnose weak cool air flow on a new Lennox A/C heat pump system after I added a new filter

I just had a Lennox heat pump with ac. I put a new filter in as the installer had not done so. Cold air is blowing out but minimally blowing. My home is all electric. I dont know what to do. On 2017-06-08 by Joyce Moorehead

by (mod) - weak cold air flow diagnosis

If the air flow reduction changed immediately in response to the filter that you installed, then it's possible that you install the wrong type of filter that too much restricts air flow. Are there other air filters in the system?

Other causes of reduced air flow are listed in this article series and include things like open or crimped duct work or a ice block or frosted coil. Those are problems for which you need help from your HVAC service technician

See the diagnosis and repair advice at

• AIR FLOW TOO WEAK

by Joyce Moorehead

The air flow was the same as before and after inserting the filter. The filter tyoe was listed on the heat pump is the one I installed. This is a brand new system. I will call a technician.

How to fix a bad HVAC control board that can't be replaced on a York Heat Pump

I have a York heat pump the control module #03101212700 (circuit board) the is bad unfortunately York stopped making the part in 2010 no replacement.

Question has any one found a bard they could wire in o make the air handler work.

The board controls the blower and heat strips during heat cycle and blower during AC cycle. wWithout this part te whole system will have to be replaced for $150 part On 2017-01-10 by john

by (mod) -

John

Yeah I am troubled by this sort of problem too - a component fails and nobody provides a replacement, forcing you to replace a much larger assembly or even an entire device.

A problem is that nobody wants to accept the very serious safety/fire/injury liability of promising you that it's ok to in essence modify a manufacturer's original design.

Another problem is that the number of people who can work on and repair old circuit boards has dwindled to almost nobody.

I recently spoke with the company who purchased Sonic Frontiers, a manufacturer of excellent tube amplifiers, to discuss possible repair of a bad circuit board in that amp. The technician at the new owner burst out laughing.

"A TUBE amplifier?", he guffawed. "We don't have anybody here who even knows what that is."

On rare occasions you might find a local electrical engineer hobbyist who is interested in trying to fix an old circuit board but it's doubtful.

Sorry. If York isn't going to offer help and if you can't find a used but working board to replace the control module in your heat pump you're sunk.

But before giving up, do some online searching for "York Heat Pump Replacement Circuit Boards" - you'll find several vendors who say they have parts.

Give a call to
Frank Switzer Owner and HVAC Technician

715-839-0934
Toll Free 1-877-839-5565
Air Dynamics Heating & Cooling, LLC
The Heating and Cooling Warehouse
1501 Nicholas Dr. Eau Claire, WI 54703

As he lists several replacement control module boards for York HVAC equipment, one of which might work for you.

You can tell him we sent you but note that InspectAPedia is an independent publisher of building, environmental, and forensic inspection, diagnosis, and repair information provided free to the public - we have no business nor financial connection with any manufacturer or service provider discussed at our website.

Watch out: some HVAC parts vendors WASTE YOUR TIME by listing at their website lines like "Replacement for York Circuit Board 03101212700" but when you actually look at the vendor's web page for that part they thumb their electronic nose, saying "Obsolete part, no longer available" - which makes me wonder why they listed it.

by John

Thanks for the info I have searched every where for this part and no luck. Though there are some web sites that say they have it but further investigation the companies are scams take your money and run I will give Frank Switzer a call.

I found a company Baytronics who said he might be able to repair the circuit board #03101212700 that appears to be my only hope at this point if Frank does not have a solution.

Still can't believe York would screw their customers like that. Will never buy a York product of any kind again

by John

Well, I lucked out Baytron (on the Web) was able to fix it and this what the problem was.

York in their infinite stupidity made the circuit board with aluminum lugs attached to the board. The heavy copper wire from the breaker panel attaches to these lugs which supplies power to the circuit. Dissimilair metals- the aluminum corrodes over time resistance builds up (heat) which melts the soldered lug of the PSB.

Adrian at Bayton could not have been more helpful (great guy) was able to attach a copper lug to the PSB resoldered it.

Just installed it and everything is working fine. Anyone who may have a similar problem let me save you the trouble of finding a replacement for part# 03101212700 there just aren't any around, been out of prodution since 2010 and no replacement. Baytron saved me thousands of $ otherwise I would be replacing a perfectly good system over a $150 part.

by (mod) -

John,

Thanks for the feed-back and added follow-up. It's particularly important to document the copper-to-aluminum problem that you found. This hazard has long been known in house wiring where connecting copper to aluminum as a "fix" for the aluminum wire hazard requires special connectors. (Summarized

at ALUMINUM ELECTRICAL WIRING HAZARD SUMMARY [web page, also that page provides a printable PDF version]

It's also particularly tough to find someone who can and will work on existing circuit boards. Good going. If your repair person at Batron wants to be identified with contact information have them let me know by email to our CONTACT link at page top or bottom of any of our pages.

by John - the repaired PSB has been working great no problems

Just a quick update the repaired PSB has been working great no problems. Now that I know the cause I will be checking it annually. Adrian suggested dielectric grease on the lugs may help.

 

Are outdoor electrical boxes used to hold the wiring and shutoff for my condenser unit really waterproof?

I was just wondering if those weatherproof outdoor electrical boxes used to hold the wiring and shutoff for my condenser unit need any special considerations when they are installed:

are they really waterproof? On 2023-09-23 by Just-Wondering -

by InspectApedia Publisher (mod) -

Steps to repair a loose outdoor electrical box used at the AC/Heat Pump Compressor Condenser Unit

@Just-Wondering,

Outdoor electrical boxes, depending on how they are mounted on a wall, may not really be waterproof.

For example I often find that water has run down the wall behind the electrical box and then leaked into the box itself.

I also find that if the electrical boxes are not mounted to the building using rust-resistant screws the screws can rust off or become loose, loosening the box and creating a dangerous electrical installation.

Here I'll outline the repair steps for a loose outdoor electrical box including those used to hold splices or an electrical shutoff for an outdoor HVAC compressor/condenser unit.

Watch out: if you are not familiar with safe electrical wiring practices you should be shocked or killed. If you're not so trained, then ask for help from a licensed electrician or an AC installer.

Having just recently removed, cleaned-up and re-installed one of those "weatherproof" electrical boxes outdoors by an AC condenser unit, I will tell you what I found:

1. The box, secured by the original installer nearly 20 years ago, was falling off of the building wall. We noticed it during an exterior painting project.

2. The installer had used interior drywall screws: they were rusted off by water running between the buiding wall and the box - which is why the box was loose.

Repair:

1. Shut down electrical power to the AC or heat pump circuit involved - else you could be shocked or killed.

See our photo below - I'm turning off power at the outdoor service switch for the condenser unit.



2. Open the box and inspect its interior for damage, loose connections, and debris.

Clean out the interior, and as the box is already loose, remove any remaining screws, taking great care not to nick or damage any of the electrical wires.

Watch out: pulling the wires around to get access to the box mounting screws can cause a twist-on connector to come loose: not only would this be very dangerous if you failed to turn off power, in addition if wires come loose it may not be obvious to you just which should be connected.

To avoid running into this trouble, if the installer hasn't already done so, for groups of wires that are connected together by a twist-on connector, we check that the connector is tight, and we use a bit of electrical tape to also tie that bundle of wires together.

3. Before re-mounting the box to the wall we clean the wall surface behind it, use fire-block foam to seal any holes drilled to pass wires if they were not sealed already, then we use an outdoor selant to waterproof the wire passages and any other damaged siding that will be behind the box.

4. Re-mount the box to the wall using exterior-rated screws

5. Use an exterior sealant (caulk) to seal the top edge of the electrical box against the wall. Sealing its sides is optional.

Do NOT add sealant along the underside of the box where it meets the wall. If any water gets into the space between the box and the wall we want it to be able to get out.

6. When pushing wires back into the box, bend them so that the twist on connector's opening is angled "down", and keep all of the connections above the bottom inch or so of the box. This keeps any connectors out of water that might enter the electrical box.

You may notice that some of these outdoor junction boxes contain an internal label with a line drawn on it -pasted along the bottom back wall of the box, and text noting that you should keep any "devices" above that line.

When those sealants are dry that's a good time to paint the wall behind the electrical box.

7. A bit of oil: With the wall sealed behind the box and the box secured to the wall and the wires properly in place inside the electrical box, drip a dab of oil on the cover securing screw so that it won't be rus ted solid fifteen years from now when you need to open it again. Then restore the box cover.

8. Restore power to the AC Circuit and confirm that your equipment is working normally.

9. Finish painting the wall around the box if that was what led you to this project in the first place

Above at the start of this discussion is my photo of the sealed top of the electrical splice box (left) and the electrical shutoff-switch for the outdoor HVAC condener unit after our reair.

Do the fuses in the local disconnect need to be the same as theBreaker or can it be less?

Do the fuses in the local disconnect need to be the same as the Breaker or can it be less? On 2023-08-06 by John -

by InspectApedia Publisher (mod) - A smaller (lower ampacity) fuse is always "safe" (but may be inadequate)

@John,

Some A/C or heat pump installations actually allow a slightly larger breaker or fuse ampacity rating than the circuit wiring would permit: to avoid nuisance tripping of the breaker during the very brief amperage surge when the HVAC compressor motor starts.

Smaller fuses or breakers bear a different note:

A smaller (lower ampacity) fuse is always "safe" in that it should blow (or breaker should trip) sooner than a larger or higher ampacity fuse or circuit breaker.

Of course if your local disconnect fuse or breaker is too small for the current drawn by the A/C compressor/condenser unit then it's going to blow or trip and your system won't work.

Watch out: if in the main electrical panel your installer used a larger amapcity breaker or fuse for the condenser unit circuit than was specified by the installation manual for the condenser unit itself then further investigation would be appropriate.

Does this heat pump disconnect violate the NEC because it's not readily accessible?

This box appears to be the disconnect switch for the Heat Pump. NEC/NFPA 70 440.17 requires the disconnecting means to be Readily Accessible.

Article 100 defines Readily Accessible as capable of being reached quickly without using tools or removing obstacles.

Heat Pumps here are being boxed into permanent sheds with a lattice about 12" from the face of the pump.

The lattice is probably screwed into place, but possibly could be torn out by hand in an emergency.

Is this installation a NEC violation because the lattice obstructs access to the disconnect switch?

After the lattice is removed, the switch is within sight of the Heat Pump of course.

If the box isn't a disconnecting switch, or any other NEC issues, please let me know! TY On 2023-01-26 by Anonymous 411

by InspectApedia Publisher - IMO YES - disconnect switch boxed into permanent sheds without easy access creates unsafe situation is unsafe

@Anonymous 411,

Thank you for the disconnect switch access question - that's helpful.

I'm not sure if your photo is one image or a composite of two images.

But it looks to me as if there is an electrical box just above or behind and above an outdoor compressor/condenser unit, not behind a lattice enclosure.

If that box can be reached readily and if, as I expect, it contains a shut-off switch or pull-out connector that can drop power to the unit, the it complies with NEC/NFPA 70 440.17

But if as your question suggests, there is not ready access to the switch without having to remove that lattice enclosure then in my OPINION the installation does not comply with NEC/NFPA 70 440.17 and is unsafe to boot.

By opening the box cover (lift "up" then "out") you should see the disconnect means. Do post a photo of the electrical box interior.

Heat Pump with electric box boxed into a shed

@InspectApedia Publisher, your expertise is greatly appreciated. Yes, it's two photos combined into one

The top photo is of a Heat Pump with electric box before boxed into a shed, and the bottom photo is of a nearby pump.

The attached new photo is of the top pump AFTER it was boxed into a shed. Note that an empty firewood bin is adjacent to the shed.

To access the electric box, I believe the lattice has to be unscrewed and removed to expose the pump and electric box. There is a chance that the lattice can be pried or ripped out. I do not have access to the pump/electric box to photograph.

Can you please briefly describe why you believe the installation is unsafe? There are 17 or so Heat Pumps in my complex, with each installed differently depending on the contractor. All pumps are boxed into a shed with lattices as shown.

Your website is a great resource! I will post a question soon to your clearance page, and how it relates to IRC, a separate issue. Thank You. by Anonymous 411

by InspectApedia Publisher - reasons why enclosed pump and disconnect switch installation is unsafe

@Anonymous 411,

Well that photo is much more clear.

Unless those covers are hinged the shutoff isn't readily accessible nor is the equipment even for service.

Worse, Even with the lattice ripped off or hinged out of the way, I'm not sure that one could reach up under that roof to get to the shutoff
in an emergency.

That installation looks unsafe to me.

Why?

First, I think that almost any code compliance inspector or electrical inspector will agree that if it's necessary to unscrew even one, much less multiple, fasteners simply to reach a service shutoff switch, the installation is not code complaint (with the US National Electrical Code) as requiring dis-assembly to access a shutoff control is NOT "readily accessible".

Second, in a practical sense, there are two reasons one would need to access the shut-off for those outdoor compressor/condenser units:

1. in normal service - the requirement that a shutoff be placed readily-accessible from the equipment it powers is intended as a safety feature, making it easy for the service technician to turn off electrical power when that's needed to work safely on the equipment -
   
   that requirement, in my OPINION probably stems from the real-world recognition that if it's hard to turn off power, some technicians will, being pushed for time and productivity, be tempted to work on the equipment with power on - that is "live", increasing the risk of injury or death by electrical shock.
2. in an emergency, should the equipment be malfunctioning, perhaps catching on fire, as an urgent safety step, someone seeing that might want to turn off electrical power to the equipment to prevent a worse disaster, such as electric arcing that sets equipment or the building on fire - again a risk to human life as well as property loss.

Now some people at your property might think that those events are un-likely to occur, and they might be right. But simply multiply a low probability by the cost of death or a building fire, and the result is still a big and serious level of risk.

Third and finally, as we have encountered firsthand in our own building service and consulting work, if, heaven forbid, there is a fire, injury, or death at your property, the second that your insurance adjuster sees that the equipment was not properly installed, was unsafe, and was in violation of the electrical code, you can figure that your insurance coverage may be considered null and void.

In some communities where code enforcement may be perhaps a bit more relaxed, I have also found that when a disaster occurs, you will never ever find the local code official standing up to be counted as having "approved" the installation.

Your property management people, on seeing this discussion, need to address these installations as soon as possible.

by Anonymous 411

@InspectApedia Publisher, the complex is located in a rural town which does not employ a Building Inspector, and is not required to do so by state law. Property Management's position has been "there is no building code."

As a result, I likely need to request state law changes due to the apparent gaps and/or inconsistencies. I will post a comment here if I get a response from the state. There is one other situation I may post if that's ok (possible missing disconnect switch). Thank You for your expertise, it's clarifying things a lot.

by InspectApedia Publisher (mod)

@Anonymous 411,

Yep I've run into that situation too: unsafe conditions where there is no building code enforcement.

In my OPINION relying on codes is, too often for all of us an "easy way out" to try to get people to do what they should do anyway.

In this case if there's no higher authority, what you have left is to be very clear to building management that you are notifying them of a well-known, well-documented safety hazard - in writing, registered, notarized, return receipt requested or hand delivered and signed-for.

That is a polite way of making clear who's going to be held responsible if a tragedy occurs and it can sometimes prompt people who otherwise are too over-worked and under-paid to take a second look.

by InspectApedia Publisher (mod)

@Anonymous 411,

In my opinion the A/C Compressor/condenser unit shutoff controls shown in these photographs are not "readily accessible", but at the end of the day, the local building or electrical inspector is the final, local, legal authority.

We have the electrical code, your photos, your opinion, my opinion, and the position of your property management.

If you have notified your property managers IN WRITING that this is a questionable, hazardous, and possibly improper installation, and there's no reply and no action, what's left is to ask your local building or electrical inspector to look carefully at the site and give an opinion.

Let us know when you've taken those two steps and what results you obtain: that will help other readers.

The box on the left appears to be the disconnect switch for the Heat Pump.

There are winter/summer photos taken at the same location.

The box is about 3-5 inches over the roof, and around 5.5 to 6 feet above the ground.

To access the box, a person has to lean against the shed on the left side, and reach up and around the corner to touch/open the box.

During winter, it's possible that the box can be buried under snow at times, and with repeated thawing and freezing, accumulated snow can have an ice layer on top and on bottom as snow compacts.

It is unknown if the snow can be pushed aside or has to be picked at with a tool to fully expose the box.

Is NEC/NFPA 70 440.17 violated due to the location of the box (readily accessible?), or because it can be buried/obscured by snow at times (not in sight at times)?

Any insight is appreciated. Thank You Again!

Are fuses allowed instead of circuit breakers?

Question: my old AC condensor is fed by a line from the house side of the meter to a fused disconnect (the kind you pull the fuse holder out to connect/disconnect). I'm replacing the unit with a new one.

My local contractor and building department(Beverly Hills, MI) tells me the power feed must be changed to feed from a breaker in the service panel to the disconnect. Is that accurate? And if so, why? Thank you - Casey On 2020-10-01 by casey powell

by (mod) -

Casey

I have found no electrical code nor manufacturer's installation instructions that prohibit the use of a fuse pull out instead of a circuit breaker.

However it is important that the ampacity or rating of the wiring and fuse or over current protection be the proper size for the equipment including any new equipment being installed.

by HMH - Copper pipe used instead of fuses in the condenser unit shutoff box

Regarding the 1/2" copper pipes in place of fuses, doesn't that mean that there are large exposed chunks of metal at high voltage?

by (mod) - copper pipes inserted in fuse clips: asking for fire or shock or death

H

Watch out: Using a copper pipe where a cartridge fuse is required means that if there is an electrical problem such as overcurrent the wiring is not protected from overheating and setting the building on fire. The risk of replacing a fuse with a piece of pipe is fire or death.

 

Can you put a disconnect before the panel and then use the same disconnect to power up your ac

By code can you put a disconnect before the panel and then use the same disconnect to power up your ac unit then feeds your panel On 2020-02-18 by Eric

by (mod) -

Eric

If I understand your question correctly, you're feeding an A/C unit from a main disconnect switch ahead of the main panel.

No don't do that.

The ampacity of the main disconnect will be sized to match the ampacity of the electrical panel, not the ampacity of the A/C unit.

For example if your main panel is 100Amps, the main disconnect will be a 100A switch.

But the A/C unit will typically be a 30A or 40A 220V device fed by wires rated to carry 30A or 40A.

Watch out: If you feed that wire and that AC unit from a switch that is rated to allow 100A you are not providing proper over-current protection to the AC unit nor to the wiring that supplies it.

The risk is an electrical fire, injury, or worse.

OK to re-use old A/C disconnect box?

Can a new A/C disconnect box be installed in the old box already mounted to the wall per national electrical code On 2020-01-08 by Jim

- by (mod) -

Jim

The "code" won't address re-using old components;

A practical answer is that if the replacement parts fit inside the old enclosure with adequate clearance then there's no reason not to-reuse the old disconnect box enclosure except perhaps cost;

in at least some cases the added labor and the cost of replacement internal parts may be higher than if the disconnect is simply replaced with a new, already-assembled unit.

Are all 20amp breakers the same or are some specific to air condition circuits - HACR or HVACR-Rated Circuit Breakers

trevose rd said: are all 20amp breakers the same or are some specific to air condition circuits On 2019-09-07 by (mod) -

Moderator Reply: no

Trevose

RE: Are special HVAC-R rated or HACR-rated circuit breakers required for air conditioners and heat pumps?

Short answer: NO you don't need a special circuit breaker for your air conditioner: all circuit breakers sized for use on residential air conditioner units will be suitable.

That's because virtually all such circuit breakers are already rated and approved for that use by having qualified / tested under UL 489.

For example Eaton Cutler Hammer, a producer of circuit breakers, says in their catalog, "All products 15-100A are HACR rated." (Source: Cutler-Hammer Miniature & Molded Case Circuit Breakers [Catalog] March 1999, retrieved 2019/09/07, original source: www.eaton.com/ecm/groups/public/@pub/@electrical/documents/content/pg74a01te.pdf)

While you may find a reference to an HVACR-Rated circuit breaker, or HACR-circuit breakers (to use the right acronym), provided the circuit breaker for your air conditioner is properly-sized, ANY conventional breaker will work fine.

When the electrical circuit for a compressor/condenser unit for an air conditioner or heat pump or refrigeration system is protected by a fuse, a special "slow-blow" fuse was installed to prevent nuisance fuse blowing during the initial high-current draw when those motors first started-up.

On changing to use circuit breakers (not fuses) in that application, to tolerate the turn-on current surge, PREVIOUSLY some circuit breakers were designed and tested specifically for their ability able to handle HVAC equipment power-on without nuisance tripping - to act like that "slow blow" fuse.

But that's no longer the case. In the U.S, Section 7.8 of the 11th edition of UL 489 granted HACR listing to ALL UL 489 Listed circuit breakers. Therefore there is no longer a requirement for special testing.

In sum, you don't need a "special" circuit breaker for your air conditioner because now ALL circuit breakers with a UL 489 listing are suitable for group motor applications requiring that HACR designation.

I emphasize "properly sized" because air conditioner compressor motors cause a brief surge in current flow at the moment of start-up that can trip the breaker.
For that reason, while a typical AC compressor unit might be wired for 30-Amp 240VAC the electrical codes permit installing of a circuit breaker one size larger (say 35A or 40A) to prevent nuisance tripping.

Take a look at the data tag on your air conditioner compressor/condenser unit, and use the Add Image button to add a sharp photo of it here.

I'll look at your data tag and together we'll doubtless see what circuit breaker is permitted.

However at least some of the circuit breaker manufacturers still make a point of LABELING certain of their breakers as HACR-rated.

Siemens provides a list of HACR-qualified circuit breakers at www.schneider-electric.us/en/faqs/FA230479/ but pretty much every modern circuit breaker has to meet UL 489.

Click to enlarge the circuit breaker label shown below and you'll see the HACR-rating

Allowable distance between the condenser unit and the disconnect switch

Can electric be ran to outdoor condenser without disconnect as long as electric panel is outside within 3 feet On 2019-08-07 by Kenny Smallwood

by (mod)

The 3 ft. might be fine but there's more to service disconnect distance: The distances between the condenser unit and the service or shutoff switch also require that the shutoff be "line of sight" and "readily accessible"

Minimum distance required for a disconnect off of a flat roof?

Is there a minimum distance required for a disconnect off of a flat roof? Disconnect is for a condensing unit. On 2019-10-24 5 by Jason

by (mod) -

You mean height from the roof surface? I expect it needs to be above possible snow height, must remain accessible, and must be in view of the HVAC equipment.

25 ft AC distance from breaker box?

I want to install an ac compressor that is 25 feet from my breaker box. Is that allowed? On 2020-05-10 by Ernest

by (mod) - switch must be line-of-sight readily accessible from the compressor unit

Ernest:

Sure, I don't see the issue, but may be I'm missing something in your question.

If you mean, not the main electrical panel but rather the service switch for the AC compressor, the switch has to be readily-accessible and in line of sight view from the compressor unit.

Beyond that, any question of distance is in the purview of your local code inspector.

A/C condenser unit distance to electric meter?

Is it code in most states for ac compressor to be a certain distance from the electrical service? On 2020-06-22 by Anonymous

- by (mod) -

Anon

A clearance distance between the AC Compressor/Condenser unit and "electrical service" (perhaps you mean the electric meter or service entry) is not given explicitly in the model codes, but there are required clearance distances and working distances.

Please take a look at CLEARANCE DISTANCE, HVAC

and let me know if you have further questions.

Thanks for asking.

Required clearance distance: A/C unit to electric service entry / meter?

Is it code in most states for ac compressor to be a certain distance from the electrical service? On 2020-06-22 by Anonymous

by (mod) -

Anon

A clearance distance between the AC Compressor/Condenser unit and "electrical service" (perhaps you mean the electric meter or service entry) is not given explicitly in the model codes, but there are required clearance distances and working distances.

Please take a look at CLEARANCE DISTANCE, HVAC

and let me know if you have further questions.

Thanks for asking.

Minimum distance for an exterior AC Compressor breaker box and a water hose bib?

What is the minimum distance for an exterior AC Compressor breaker box and a water hose bib? On 2020-06-29 by Bob

by mod

That's not given explicitly but see the HVAC CLEARANCE DISTANCES we linked just above

 

OK to put the condenser unit disconnect under a window?

Can a 40amp ac disconnect be located under a working window On 2019-06-27 by Red -

by (mod) -

With the ducking and weaving that comes with not being able to actually see the installation that you're talking about and a warning that of course there could be something there that is unsafe, I haven't found any restriction that prevents locating an emergency shut-off for an air conditioner outside compressor condenser unit below a window.

Regulation that requires the electric disconnect switch to not be located behind the exterior condenser unit?

Is there a regulation that requires the electric disconnect switch to not be located behind the exterior condenser unit? On 2018-05-28 by Joseph Scaduto (ASHI)

by (mod) -

Hi Joe, nice to hear from you. I am nervous answering a question from an educator who knows more than I do, but here's my OPINION:

MAYBE:

Regulations for safety disconnect switch location require that the switch be readily-accessible.

If in a particular case, locating the disconnect behind the condenser unit has jammed it into a location that would not be readily accessible then that location is improper.

There has been a lot of chatter about where the switch must be, including just what is meant by "readily accessible" to include - within line of sight.

The intention of the electrical code such as NEC 440.14 (also see NEC 430.102) for these switches is two fold

1. having a switch that's readily accessible reduces the temptation of some techs to work on equipment live, hopefully reducing shocks and fatalities. It can be some distance away but must be visible from the A/C unit. There is a similar rule for room air conditioners that adds - Within 6 ft. of the floor.

2. in an actual emergency that might occur during service (this happened to me on a heating repair job) you want the tech to be able to turn the system off immediately - like "HELP MY TIE IS CAUGHT IN THE FAN"

Cost to replace a circuit breaker at the outside heat pump shutoff

My landlord took pull out circuit breaker out of unit outside how much do they cost On 2017-07-17 by rainsgwendolyn3@gmail.com -

by (mod) -

It depends on type & capacity, $5 TO $150 plus cost to pay the electrician for her time or labor.

Watch out: do not try working in an electrical panel as you could cause a fire or be killed

 

Question: replace the cover or door of an A/C cutoff box

Can I buy just a door for a/c cut off box (Sept 7, 2016) Nola said:

Reply:

If you are referring to an indoor or outdoor electrical power switch, check with your local electrical supplier.

If you are referring to the compartment cover or door of an air handler, possibly so, if you can read the manufacturer's name and box model number, just give the manufacturer a call.

 

...

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Continue reading at CONTROLS & SWITCHES, A/C - HEAT PUMP - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see A/C HEAT PUMP CONTROL / SWITCH FAQs-2 - more questions and answers about switches and controls on air conditioners and heat pumps.

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Recommended Articles

• A/C - HEAT PUMP CONTROLS & SWITCHES
  • OUTSIDE HVAC SWITCHES & CONTROLS
  • INSIDE SWITCHES & CONTROLS
  • OPERATING CONTROLS, A/C & HEAT PUMP
• ELECTRICAL POWER SWITCH FOR HEAT
• OPERATING CONTROLS, A/C & HEAT PUMP - home

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