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

First here are some helpful A/C and heat pump diagnostic procedures:

If your air conditioning or heat pump system has lost its cooling capacity or won't start select one or more of the diagnostic articles listed below.

• DIAGNOSTIC GUIDE A/C or HEAT PUMP - Air conditioning and heat pump diagnostic procedures - start here if the system won't cool.
• A/C DIAGNOSTIC FAQs: air conditioning system diagnostic FAQs: Q&A about air conditioner repair - a detailed air conditioning system diagnostic checklist
• AIR HANDLER UNIT: problems with the air handler, air filters, and the cooling coil itself
• BLOWER DOOR SAFETY SWITCH - interlock shuts off the indoor air handler if a blower door is open
• CONTROLS & SWITCHES: air conditioner controls and switches - or begin here if your A/C won't start. Here's an important tip: most refrigeration problems, in air conditioners, refrigerators, or freezers, are electrical, not mechanical. In air conditioning school, we used to drive out and collect abandoned refrigerators that people were tossing out during our community's spring cleanup week.
  
  Taking these appliances back into the shop we found that almost always the problem that had caused the owner to dispose of their air conditioner or freezer was in an electrical connection or electrical control. So it's worth checking out switches and controls on an air conditioner before replacing more costly components.
• COMPRESSOR CONDENSER: problems with air conditioner compressor/condenser units
• DUCT SYSTEM DEFECTS: problems with the air duct system, air filters, supply registers, return air registers
• LOST COOLING CAPACITY: what to do when not enough cool air comes out of the system or the A/C just won't work at all
  • WHAT to CHECK FIRST if there is no cool air or not enough cool air
  • COMPRESSOR FAILURE DIAGNOSIS basic checks of the air conditioner compressor
  • DUCTS & AIR HANDLER DIAGNOSIS: basic checks of the indoor air handler (blower), air ducts, and filter systems
• OPERATING DEFECTS: major air conditioning problem symptoms and how to get the air conditioning system working again,e.g. compressor or fan noises, failure to start, and inadequate cool air volume
• OPERATING CONTROLS, A/C & HEAT PUMP for a discussion of thermostats, zone dampers, and circuit breakers on air conditioners and heat pumps.
• A/C REFRIGERANT LEAK DETECTION: how to use a TIF5000 to detect air conditioning refrigerant gas leak
• THERMOSTATS and THERMOSTATIC EXPANSION VALVES.

On 2019-08-01 by (mod) - Why is my heat, or backup heat, turning on when we're in cooling mode?

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.

On 2019-08-01 by Bill

What would cause an A/c unit when in cooling mode and operating to also turn on the heater in air handler?

On 2019-07-17 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.

On 2019-07-17 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.

On 2019-07-09 by Bryon

Replaced the thermostat and now the unit is not working

On 2019-06-23 by (mod) - Compressor does not work. Cooling fan does.

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.

On 2019-06-23 by Tim

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 2019-06-15 by (mod) - heat pump water reservoir

I'm not sure I have the correct understanding of your question.

But if you are asking where is the reservoir of water used by a heat pump in a water based heat pump system there are two approaches that are common.

One is water that's actually pumped out of and back into a well.

The other is water that's pumped from a well into a reservoir tank and recycled from the tank through the heat exchanger coil in the heat pump.

On 2019-06-15 by Phil

Where is the amount of water a water based heat pump gets controlled?

On 2018-07-03 00:43:52.755527 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.

On 2018-07-02 by Chris Jeffrey

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 2017-12-05 by (mod) -

See A/C HEAT PUMP CONTROL / SWITCH FAQs at https://inspectapedia.com/aircond/Air-Conditioner-Switch-FAQs.php

On 2017-06-23 by James

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 2017-06-09 by (mod) -

Thanks for the follow-up, Joyce. Do let us know what you're told as that will absolutely help other readers.

On 2017-06-09 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.

On 2017-06-08 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

On 2017-06-08 by Joyce Moorehead

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 2017-04-06 by Antony

AC comporsor line image

On 2017-02-06 by Ray - My a/c compressor continues to run even after thermostat is turned to heater.

My a/c compressor continues to run even after thermostat is turned to heater. The blower motor works fine and it shuts off like a normal cycle so I don't always think to check outside to see if the compressor is still running. When I do, and it is, there is ice on the tubes going under the house

. I replace the filters every 90 days religiously. In fact, New filters went in yesterday. Heater at night, a/c in the afternoon... have to love New Mexico weather. Compressor only shuts off when I cut power at the switch outside. I replaced the motor run capacitor 4 years ago and then again last year.

4 years ago the a/c company sent a guy to check (free) to make sure everything was working right. He said he would only charge me if the freon level was low, which of course he claimed it was.

Last year I did not call the company and just changed the capacitor & cleaned the coils (both sets). Anyway, can you help figure out why compressor outside will not shut off & ices up?

The heater and a/c were replaced in Aug. of 2006. Made by York and is a 4ton unit (too big, damn salesman). When everything works right, it is great, but my electric bill is outrageous. Should I consider another replacement unit or just hire a different company to do a service call?
Thanks for any help you can give me.

On 2017-01-22 1 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.

On 2017-01-13 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 https://inspectapedia.com/aluminum/Aluminum_Wiring_Summary.html_

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.

On 2017-01-13 by John

Well, I lucked out Baytron (on thw 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.

On 2017-01-13 by (mod) -

John

Thanks for the follow-up; do let me know what happens as what you learn will help other readers too.

On 2017-01-12 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 appaers 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

On 2017-01-10 by (mod) -

John

It is indeed frustrating when 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.

On 2017-01-10 by john - need a York heat pump control module replacement that York no longer provides

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 obard 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 2017-01-12 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 appaers 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

On 2017-01-10 1 by (mod) - how to fix a bad HVAC control board that can't be replaced

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.

On 2017-01-10 by john

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

...

...

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

ELECTRICAL POWER SWITCH FOR HEAT

CAPILLARY TUBES

The main operating controls for HVAC systems and their functions are are discussed at OPERATING CONTROLS, A/C & HEAT PUMP where you will find a discussion of thermostats, zone dampers, and circuit breakers on air conditioners and heat pump systems.

Other air conditioning and heat pump diagnostic procedures are at LOST COOLING CAPACITY.

Or see these

Recommended Articles

• A/C - HEAT PUMP CONTROLS & SWITCHES
  • OUTSIDE HVAC SWITCHES & CONTROLS
    • COMPRESSOR CONDENSER CONTROLS, SWITCHES
    • COMPRESSOR DISCONNECT SWITCH
    • CONTACTOR RELAY DIAGNOSIS & REPAIR
    • KEY HVAC SWITCHES service switches, circuit breakers, fuses, power
    • REFRIGERANT PRESSURE CONTROLS & SAFETY SWITCHES - separate article
    • REVERSING VALVE on HEAT PUMPS
  • INSIDE SWITCHES & CONTROLS
    • AIR HANDLER UNIT SWITCHES
    • BLOWER DOOR SAFETY SWITCH - separate article
    • BACKUP HEAT CONTROLS
    • CAPILLARY TUBES - separate article
    • CIRCUIT BREAKER SIZE for A/C or HEAT PUMP
    • CONDENSATE PAN OVERFLOW SWITCH
    • DUCT SYSTEM SWITCHES
    • DUCT SYSTEM FILTERS
    • SPILL SWITCHES on AIR HANDLERS
    • STARTER CAPACITORS
    • THERMOSTATS & CONTROLS
    • THERMOSTATIC EXPANSION VALVES
    • MOTOR OVERLOAD/ OVERHEAT RESET SWITCH
    • ZONE DAMPER CONTROLS
  • OPERATING CONTROLS, A/C & HEAT PUMP

Suggested citation for this web page

A/C HEAT PUMP CONTROL / SWITCH FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to AIR CONDITIONING & HEAT PUMPS

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