Air Conditioner & Heat Pump Electrical Problem Repair FAQs

Q&A on how to Diagnose & Fix Air Conditioner & Heat Pump Electrical Failures

A/C or Heat Pump Electrical Failures: current draw, high amps FAQs

Air Conditioner / Heat Pump Current Draw Issues

If the compressor is rated for 14Amp and is running at 11.8 Amp dose this mean the compressor is ready to burn out?

If the compressor is rated for 14Amp and is running at 11.8 Amp dose this mean the compressor is ready to burn out? - by jim

Reply by (mod) - no

Jim:

About your question "If the compressor is rated for 14Amp and is running at 11.8 Amp dose this mean the compressor is ready to burn out?"

Not in my book. Usually when a compressor is seizing up it will draw abnormally high amps not lower amps. Take a look at the RLA figure for your unit.

Follow-up comment by jman

To jim no that the rating for design conditions was the temp outside 95 if not then it is good

Followup by jim Hanlon

Jman the outside temp was over 95

Compressor has failed mechanically (drawing far too many amps).

Just a follow-up for future readers. Compressor has failed mechanically (drawing far too many amps).

My no-name (builder grade) outside unit trys to start but won't.

The fan runs fine (I replaced it last year)but the compressor tries to start for about 2 seconds, then stops. About 45 seconds later it will try again. Same results. It never trips the breaker.

I had a tech come out while I was at work and he "thinks" the compressor is locked up. I checked the resistance today and got .001 C-R, .002 C-S, and .002 R-S. My DMM reads OL (overlimit) when checking all three terminals against the compressor case.

I'm leaning toward low refrigerant (is there a low pressure shut-off on home systems like in cars?).

Tech that came out told the wife it wasn't low on refrigerant but...? I'm gonna swap a known-good Run-start cap from my other unit and try that. I guess the compressor could've failed mechanically. Any thoughts? - On 2011-06-06 by Richard -

Reply by (mod) - a high amp draw on the compressor circuit

Thanks Richard for the followup A/C diagnostic detail. Indeed a high amp draw on the compressor circuit is one of the basic diagnostic tests that lead a tech to think the unit is seized or failing.

The high pressure (smaller diameter) refrigerant line is not normally cold in cooling mode but could be warm or even hot depending on where along its length you are checking on its temperature.

The low pressure or suction line (the larger diameter refrigerant line) is normally cold when the air conditioner has been running for a while and can even show frost on uninsulated sections.

I'm not sure from your description if I can say that the high pressure warm line is a problem, but if your low pressure line is never getting cold I suspect a lost refrigerant charge (or the compressor is not running at all).

Air Conditioner Compressor trips the breaker

The outside compressor/condenser unit of my central air conditioner, which is wired to a bi-pole 30amp circuit breaker, started to trip the breaker whenever the indoor thermostat turns ON the air conditioner. Never had this issue in the past 6 yrs.

Despite the breaker being tripped, there's air coming out of the supply registers, but it's warm obviously due to the compressor/condenser unit being tripped OFF.

What could be some reasons for tripping the breaker?

One strange condition I noticed is that when the indoor thermostat is switched to OFF (not on Cool), the breaker stays ON without tripping, and the compressor/condenser unit's fan rotates at about medium speed, instead of being OFF.

Any suggestions or help will be appreciated. - by TN_Goose

Reply by (mod) - Check current draw at the compressor and check possible bad control board

TN_Goose:

It sounds as if your outside compressor/condenser is not starting; a compressor that has seized or is drawing high amps would trip the breaker.

I'm baffled about why the outside compressor fan would run at all when the indoor TT is set to OFF; could be a bad control board or circuit or one that was damaged during compressor burnup.

Followup by TN_Goose What would cause the compressor to seize or burnup?

Thank you for the quick reply. When you say "bad control board or circuit", are you referring to the ones in the compressor/condenser or TT?

Would a faulty capacitor (one that might be almost ready to fail) cause the compressor fan to run? It's really odd for the fan to run with TT set to OFF. I opened the outer casing of the compressor/condenser today and checked the apprearance of the capacitor (looks fine - .no bulging or corrosion anywhere...couldn't check for the MFD

Waiting on the just purchased HVAC/R multimeter shipment), and all wiring connections from the compressor and the fan look OK (no shorting or loose connection).

What would cause the compressor to seize or burnup? I'm wondering if the extreme hail storm and heavy rain that partially flooded outside compressor/condenser area (about 3-inches of water) has anything to do with it.

Reply by (mod) - seized motor: bad bearing, liquid slugging, bad lubrication, wrong voltage, other causes of A/C compressor failure

Typically for the symptoms you described, if it's not a thermostat problem, the service tech will probably do some simple electrical tests of the compressor/condenser unit, check system pressures, and will visually examine the controls and circuits in the outdoor compressor/condenser unit for an obvious problem before doing more sophisticated tests.

FYI sometimes a capacitor can be bad without bulging.

Compressors can seize from internal wear, a problem that can be accelerated if there is moisture or if there are contaminants in the refrigerant.

Followup by TN_Goose - check the start capacitor first

I'm going to check the capacitor MFD first, then if it's not the capacitor issue, I'm going to call Hiller Air Condtioning. I'll post the result of the root cause finding. Thanks again for your help.

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 . - 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/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. by Tom F

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.