Air Conditioner & Heat Pump Repair FAQs

Diagnose & Fix Air Conditioners & Heat Pumps Set#1

A/C or Heat Pump Electrical Problem FAQs

A/C fan not working and smoke is coming out with noise.

At my condenser unit the fan is not working and smoke is coming out of the unit and it's making a strange . - On 2012-10-14 by maria

Reply by (mod) - Unsafe Compressor/condenser Unit Operation: Turn it OFF Immediately

Maria,

In cases such as you describe,

Watch out: Shut that system off immediately - There is serious risk of an electrical fire.

Turn off electrical power to your compressor/condenser unit right at your electrical panel.

If smoke continues, call your fire department from a safe location outside the home.

When power is off and there's no remaining fire risk, then call your HVAC service company, tell them what happened, and ask for help from an experienced repair technician.

I suspect that the condenser unit fan motor has seized and burnt-up but there may be other damage to wiring or controls.

 

A Fried Lizard shorted out the capacitor in our compressor unit, now we have no A/C

I found a fried lizard laying across what appears to be the terminals to a large capacitor. The AC will not kick on. Could this have shorted it? It is a RUUD unit. On 2012-07-22 by Viv

Reply by (mod) -

Viv,

Yes indeed an animal shorting out electrical wiring terminals at a start/run capacitor can destroy the capacitor or other components.

Call your HVAC service company for repair help. It might be that all that's needed is a new capacitor.

 

A/C stopped working: Squirrels chewed up the thermostat wire: blew a fuse at the furnace

What the heck?

Squirrels chewed up the thermostat wire going to the condensing unit at a rental house we have. I repaired the damage and replaced the blown 3 amp fuse on the control panel at the furnace.

The air still would not kick on.

I poked around a little more looking for other obvious causes but could find none. I gave up and called the company that installed the system 3 years ago. I scheduled an appointment for Monday (today is Saturday) and went on about my business.

My tenant just called and said the air suddenly kicked on and everything seems to be fine.

I was just curious as to what could have caused that delay. It was a couple of hours from the time I did the repair until it kicked on. On 2012-06-09 by TomF -

Reply by (mod) -

Tom, indeed as we learned from our local telephone company, there are some wire insulations that are very attractive to squirrels and other rodents.

About the delay - maybe a bad connection or other damage that you haven't yet found?

Intermittent electrical faults can be difficult to spot. Ask your tenant to let you know promptly if the system stops working again so that there's a better chance of finding the problem.

 

Is it common to see compressor ground out after replacing condenser fan?

Question-Is it common to see compressor ground out after replacing condenser fan?

Carrier AC-Fan was making screeching sounds periodically, and also only operating at 70%, so had it replaced.

Condenser also replaced.

When tech installed new fan, it was confirmed by error code with Carrier, that compressor grounded out.

Tech said that with the high amperage coming off new fan, compressor was used to the amps coming off old fan, and it grounded out because of this.

I don't know a lot about AC units, and compressors, but could my contractor have caused the compressor to ground out? 2017-06-09 by Ron

Mod reply:

I don't think so, Ron, those sound like separate problems.

However if there was an "event" like a lightning strike that might damage both the fan motor and the compressor motor.

Yes a mistake during work on any electrical equipment might accidentally touch a live electrical component to ground, causing damage or worse, a shock. But of course we can't know by a simple e-text what your contractor was doing nor if there was any possibility at all that she caused the trouble you describe.

A/C or Heat Pump Weak Air Flow FAQs

Our A/C unit is not drawing air through the return air inlet and filter

A/C unit does not have intake suction from inside of home where filter is located. On 2012-09-13 by Anonymous

Reply by (mod) - air conditioning system has NO return air taken from inside the home

Anonymous

If you are saying that your air conditioning system has NO return air taken from inside the home, that's not a reasonable design - too costly to operate;

If you are saying that there is no air flow in to the return air inlet, then I suspect there is a dirty filter or a duct disconnection or leak problem to find and fix.

So what's needed is

1. Check for a dirty or blocked air filter and replace it with a new clean filter

If that doesn't fix the problem then

2. Call your HVAC service company and ask for diagnosis and repair help; you may need to have the blower fan cleaned or there could be a duct system that's blocked or disconnected, or the blower may not be working at all

- Daniel

To Improve air flow I ran the A/C system with no air filter - how can I fix the system?

Just got done replacing my condenser fan motor and capacitor...finally I have cold air again.

Removed the filter from the inside unit as it was dirty but didn't have a new one, so let it run a few hours with no filter.

Two rooms in my house have always been 'hot' due to low airflow from the registers, but just dealt with it for many years. (I have tried both expensive, cheap, reusable filters - same result.)

I checked the airflow from these registers (with no filter in place) and there was GREAT airflow, and the rooms were both quite cool.

I bought new filters and installed one, then checked airflow in these rooms again.

As always, very poor airflow.

Since my electric bill was $400 this month (of course it's the hottest June in Colorado on record) I'd like to help with it's efficiency.

So, my AC has restricted airflow when the filter in place, and my AC is working harder than it needs to.

What, if anything, can I do to help this situation? I certainly can't go for long without a filter...any advise is appreciated. On 2012-07-20 by Mike -

Reply by (mod)

@ Mike

Watch out: running your A/C or heat pump system without an air filter will cause both the blower fan blades and the evaporator coil itself to become dust clogged. Ultimately that blocks air flow and will require a service call to clean the system properly.

Once that hsa been done:

I would look into replacing the filter with a more flow-efficient type that would increase the airflow and still provide proper air filtration .

It could be that you are using HEPA rated filters rather than standard filters, and if you dont need the HEPA rated filtration you could quite nicely do without it...

Aside from that option, replacing your fan or blower unit may prove feasible.

It may be that your current fan or blower is dying on you or you just need a more powerful unit to blow air through thick air filters (especially if you are using HEPA filters and you need to keep them for health concerns...)

AC was getting weak. We shut it off over-night. In the morning it was working.

AC was getting weak. We shut it off over-night. In the mourning it was working. Kept apt. with tech that we made the day it stopped.

He sucked water out of the PVC were discharge water comes out from the AC. 3 weeks later, AC blowing warm air again.

Tech came, showed me the condenser(?) - (that small can about the size of a 6oz drink) was swollen.

New condenser(?) installed & it worked again, for a week. Now it stopped blowing cold air again. All three times it rained heavy.

Made sure the water from the unit can get out since I suspected rain water might be preventing the run-off water from the AC unit to get out.

Also sucked it with a shop vac. This time and previous, fan in the compressor (the lager unit outside) was not rotating. The first time it was shutting off & on in approximately 5 minute intervals. What's causing this? could wrong amperage (but I did not change anything) blow the condenser?

Could water short-circuit the unit? If so, why did this not used to happen but is now? It ran fine during hurricane Irene. On 2012-08-28 by Irene

Reply by (mod) -

Irene,

First: check your air filter:

When the air flow is weak but returns strong after the system has been shut down for hours the most-likely explanation was that the cooling coil (evaporator coil at your indoor air handler) was blocked by frost or ice - as can happen if there is a refrigerant leak or if the system was run without a good air filter.

Next: understand the repair that was already made:

What you refer to as the "condenser" that was swapped out was probably a start/run capacitor - an electrical component.

Often a new capacitor can get an iffy electrical motor running again by giving it an extra electrical "kick" to get spinning. But if the motor is fundamentally failing, say by a bad internal bearing or some other problem, eventually even the new capacitor won't get it working. The bad motor will need repair or more likely, replacement.

At your outside A/C unit listen to hear what's happening - if you hear a humming there is a motor unable to start.

When a fan won't start we suspect a bad start/run capacitor for that motor, or a bad fan motor or bearing itself.

The condensate drain problem is a separate issue.

 

What are the Standards for Air Conditioning System Cooling Capacity or capability required for rental units?

My rental property management agency told me that my unit's AC capacity is only required to cool my townhouse (1800 sq ft) to 15 degrees below the outside temp. Is that correct? I don't believe them. On 2012-07-19 by Brent

Reply by (mod) -

Brent:

On Standards for Air COnditioning System Cooling Capacity or capability required for rental units

There is no national code or standard for the cooling capacity nor turn-on date for air conditioning in rental units, though there may be state or local housing authority standards for cooling in your municipality - that's something for you to ask your local building department or rental housing authority.

Indeed if a cooling system is under-sized it is likely to be unable to keep up with cooling your rental unit in very hot weather. The actual ability of an air conditioner to cool an occupied space is of course affected by the properties of the building as well as the air conditioner.

So picking an A/C unit's BTU cooling capacity, normally based on square feet alone, can get us in trouble if the particular building has lots of sun-exposed windows, or other reasons for high heat gain.

Certainly in our research to answer your questions we found some municipalities where there is a local rental unit housing authority to whom complaints should be addressed if a landlord refuses to respond to an air conditioning operating problem in a reasonable amount of time.

E.G. quoting from Montgomery County Maryland:

To file a complaint, please provide a brief description of the problem, the address where the violation is occurring, along with a specific location (if applicable). The caller's name and phone number are requested so that the inspector can call and provide an update of their findings or, if this is a rental property, to schedule an appointment.