Air Conditioner Circuit Breaker / Fuse FAQs

Q&A on air circuit breaker trip or fuse blowing on conditioners & heat pumps

Air Handler / Blower Unit Trips Breaker or Blows Fuse FAQs

Useful Diagnostic Articles

• CONTACTOR RELAY DIAGNOSIS & REPAIR
• CONTROL CIRCUIT BOARD, A/C
• ELECTRIC MOTOR DIAGNOSTIC GUIDE

A/C Unit keeps blowing fuses whenever I turn it on

My 3A fuse keeps blowing when turn AC on? - On 2019-06-07 by Rich

Reply by (mod)

Watch out: Rich; when a fuse keeps blowing there is either a short circuit or a seized motor that's drawing so much current that the fuse blows or circuit breaker trips - to prevent a fire.

Leave the A/C off and call for repair.

Air conditioner trips circuit breaker after 30 minutes

What causes an airconditioner to go for a short time then stripe the breaker after 30mins or so? On 2011-08-05 by Dominic O Setshego

by (mod) - A/C keeps tripping the breaker

Dominic, if your A/C keeps tripping the breaker there is probably an electrical current overload - could be a compressor motor failing, overheating, or having trouble starting.

Turn off the system to avoid an electrical problem or fire and get a service tech out to diagnose the issue.

Air Handler blower motor keeps blowing fuses

I have Goodman Air handler & My blower motor contorl board keeps blowing fuses.

I have replaced control board, transformer, contactor, capacitor, t-stat, breaker, disconnect, the unit was working for about 5 days now it keeps blowing fuses on the board it will work 4 about a day then blow another fuse. HELP? On 2011-08-02 by Anthony Goodman

by (mod) - diagnostic steps for HVAC equipment that keeps blowing fuses

Anthony I think if your equipment keeps blowing fuses and there is no evidence of a short circuit in the wiring itself I'd suspect that the equipment is drawing high amps - which points to a bad motor.

Ask the service tech if s/he has measured the current draw on the system.

by Anthony

I have checked it, it's normal

by (mod) - more causes of blown fuses on A/C system

A: as you know, a fuse will blow from either an instantaneous hard short circuit or from an overcurrent that occurs over a longer period of time.

So it would seem there's either an intermittent short or an overcurrent, or an intermittent overcurrent.

It would probably help to look at a circuit diagram to see exactly what that control board fuse is protecting - what's on that circuit.

My A/C unit kept blowing a fuse, now nothing runs

My Center A/C unit had a tuned up. I clean the evaporator, I put the blower down and put the new motor and clean the blades deeply, I have a clean filter, I clean the condenser deeply, and I bought a new thermostat. OK.

The unit starts running normally and you feel the normal warm air at the fan (outside)

But 3 to 5 minutes later the heat in the condenser air increased suddenly the condenser stops with noise, and I need to turn it off. What is this? Please give me a clue? - Anon 6/28/22

I have a pretty old Tappan unit, and when the power goes out, if the A/C is running it will blow the fuse, usually we just replace the fuse, and now nothing will run on the A/C unit. any ideas? - Shantel 6/20/11

Reply:

Shantel:

Often when an A/C unit keeps blowing the fuse it's a sign that the compressor is drawing high amps which means it's jamming which, I'm sorry to say, means it's at end of its life. I'd have a service tech look at the unit; it might limp along for a while longer if s/he installs a hard-start capacitor kit.

When "nothing runs" you may have meant that the fuse or breaker tripped enough times that you've lost power on that circuit.

Anonymous - from what you describe you need a service call from a trained HVAC tech.

A/C Blower Unit Fan inside is on but no air flows and a circuit breaker has tripped

I'm in office building. Each unit has own ac unit outside. I turned it on and it worked for two days no problem.

Today it stopped cooling. The blower fan inside is on but there's no air flow. Air Conditioner unit outside is OFF. It makes no sound when turned on. I checked panel for tripped switches.

In the electrical panel left side a breaker labeled A C had two single switches pinned together. They're labled a c and heat.

It looks like this switch was tripped. T n 2019-06-12 by tony

by (mod) - Circuit breaker tripped off means there's an electrical problem to find

Tony

If the indoor air handler blower fan is really "ON" some air should be coming out of the supply registers unless

• The duct system has become blocked or disconnected
• The blower fan motor is running but the fan itself isn't spinning, for example if a drive belt type fan has a broken fan belt

But

Watch out: For safety, leave the system OFF.

When a circuit breaker has tripped that usually means there's an overcurrent.

Even if you can turn the AC back on by resetting the breaker there is an underlying problem that needs to be found and repaired.

It's time to call for service.

What is causing high electrical current draw (amps) at my air conditioner?

My AC is rated at 8.5 ampere. But now it is consuming up to 13 amperes of current.

Due to this stabilizer gets overheated within 1 hour. Please tell me about the defects. On 2012-06-05 by Rickey

by (mod) -

Rickey, several problems can cause high current draw at an A/C system; some high current is normal at motor start-up at the compressor/condenser unit, for example.

But if the run current is abnormally high, I'd suspect that the compressor motor is binding (failing), or there is a refrigerant metering valve control problem causing high head pressure against which the compressor motor is working too hard and drawing high current.

Diagnose Lennox A/C that sometimes blows the fuse

I Have an older Lennox 5 ton unit. Sometimes when the unit starts it will blow hot air for 20 minutes then it would start cooling but not every time. On some occasions it would blow the fuse. - Jesse

Reply by (mod) -

When a motor is blowing a fuse or tripping a circuit breaker I suspect that there is a failing bearing or other motor component that is drawing excess current and thus blowing the fuse.

It could be the compressor motor or the fan motor that's having trouble starting or has a motor failure. Sometimes the tech will try a quick fix by installing a motor hard start capacitor.

Followup by Jesse

I have a guy coming to look at it tomorrow. So you think it could be in an internal shut off even though the unit runs fine it satisfies itself with the temperature, turns itself off then when it turns itself back on (not every time) it'll run hot for the 20 minutes and then start cooling?

I will definitely let you know what the guy tells me tomorrow. Thank you for the reply

Followup by Jesse - Tech found a loose HVAC duct opening

So the tech came out he replaced a capacitor a relay and for some weird reason there was a panel that wasn't screwed down in the intake that was opening every once in awhile like a 3-foot gap letting in hot air once he did all those things the AC hasn't blown fuses and has been running fine

 

Compressor/Condenser Unit Trips Breaker or Blows Fuse

Diagnostic Starting Point:

• BURNED-OUT COMPRESSOR
• CONTACTOR RELAY DIAGNOSIS & REPAIR
• CONTROL CIRCUIT BOARD, A/C
• ELECTRIC MOTOR DIAGNOSTIC GUIDE

Also see COMPRESSOR / CONDENSER UNIT ELECTRICAL FAILURE FAQs - other than blowing fuses

As soon I turn the power switch ON the condenser unit trips the circuit breaker

I have a heat pump. The outside unit is on one breaker. An the inside unit is on another breaker.

The out side unit is tripping the breaker. An when I try to reset it it immediately trips again. I don't even have time to get my finger off it before it trips. Or I can pull the disconnect switch an it won't trip

As soon I put the switch back in. It trips the breaker. I can leave the disconnect switch in an unhook the 3 wires to the compressor at the control panel on side of unit.

An the breaker doesn't trip.

But soon. As put the wires back on the breaker will trip. O

ther than having a bad compressor. Can anything else cause this problem. On 2017-01-08 by Anonymous

Reply by (mod) -

Anon:

It sounds like the problem is a seized compressor motor in your outside condenser unit.

But yes ,other failures at the condenser unit could trip its circuit breaker such as a shorted or failed fan motor, control board, relay, or even the electrical power wires themselves.

Watch out: for safety, leave the condenser unit circuit breaker OFF and call your HVAC service company for repair.

Compressor unit trips the circuit breaker on hot days

HELP! My home is ancient and small (-1000sqft), it is wood with little or no exterior wall insulation, the a/c is 20+ yrs old.

The compressor/condenser unit has begun to trip its breakers in the heat of the day when it gets to 105+ degrees and when it is running it is nearly impossible to get the house below 85F. Am I short on coolant? On 2011-08-03 by Eric Fisher

Reply by (mod) - compressor is tripping the circuit breaker

Eric if the compressor is tripping the circuit breaker it may be at end of life - but a service tech should check the system before replacing anything.

That's not a low refrigerant issue, it's a failing motor problem.

Watch out: don't just keep re-setting the circuit breaker or you risk an electrical fire.

A/C compressor trips the circuit breaker, what might be wrong?

my compressor shorts out my breaker, I tested the compressor with an ohm meter and reads voltage. what can it be? - Chico

Reply: seized electric motor?

Chico: if your air conditioner compressor shorts out and trips the circuit breaker I'm afraid the compressor motor may be seized.

That causes a high current draw when the motor is trying to start, and that trips the circuit breaker.

My A/C unit kept blowing a fuse, now nothing runs

My Center A/C unit had a tuned up. I clean the evaporator, I put the blower down and put the new motor and clean the blades deeply, I have a clean filter, I clean the condenser deeply, and I bought a new thermostat. OK.

The unit star running normally and you fill the normal warm air in the fan (outside) But 3 to 5 minutes later the heat in the condenser air increased suddenly the condenser stop with noise, and I need to turn it off. what is this? Please give me a clue? - Anon 6/28/22

I have a pretty old Tappan unit, and when the power goes out, if the A/C is running it will blow the fuse, usually we just replace the fuse, and now nothing will run on the A/C unit. any ideas? - Shantel 6/20/11

Reply:

Shantel:

Often when an A/C unit keeps blowing the fuse it's a sign that the compressor is drawing high amps which means it's jamming which, I'm sorry to say, means it's at end of its life.

I'd have a service tech look at the unit; it might limp along for a while longer if s/he installs a hard-start capacitor kit. When "nothing runs" you may have meant that the fuse or breaker tripped enough times that you've lost power on that circuit.

Anonymous - from what you describe you need a service call from a trained HVAC tech.

AC Compressor makes weird nose and shuts off

Hi, My AC comes on normally and runs between 15 and 30 mins. Then my compressor makes a weird noise and everything loses power without tripping the breaker.

The display goes off and the compressor will not turn on. After about an hour everything comes back on and the cycle continues. Please help me. by Phil

Reply by (mod) - overheating motor

This sounds as if a motor is overheating and tripping an internal thermal overload.

That would explain why after a cool down period the system will run again.

I'd ask for a service call - of course the problem could be elsewhere (such as an overpressure and shut down by a safety control) so let me know what you're told.

First sign something was wrong with our Goodman A/C was the abrupt noise.

BTW, the tech told me this older unit did not have the safety control. The new unit they installed is a Goodman 14 SEER.

Both guys that installed the newer unit came out. They were baffled. One of the techs did his pressure or whatever test and showed me the needle not moving (exactly what I was shown when the other unit died).

Our first sign something was wrong was the abrupt noise. It's not been that hot here, so we couldn't judge if it was cooling or not.

The unit, however, on about 50% of the time, from when they gave it the OK on Saturday and it failed Monday night.

Weird, not much pops up when you Google anything related to the fan motor causing this. FYI: A friend recommended these guys who has used them for 4 years. - by JH

Reply by (mod) -

It's not a complete surprise for two pieces of equipment made at the same factory on the same date to fail close together in time.

I've seen that failure pattern in other situations, even the electrical spark plug points contact spring in my old Norton motorcycle.

One spring broke (of course far from home and on a trip) - we were clever enough to buy replacement points sets for both left and right cylinders and lucky enough to find a place to buy them without getting arrested - but that's another story.

We took of down the highway, having replaced the right hand points set. In less than 50 miles the other set failed in the same way.

It's also imaginable that a power surge such as during a thunderstorm or from the electrical company or caused by human error working on equipment damages a capacitor, control board, relay, that in turn causes subsequent major parts failure.

EG a surge that damages a start cap can in turn mean the bad cap ultimately leads to motor failure.

If I wasn't clear earlier, a system will overheat when the fan isn't working. Overheat -> damage.

All of this is SPECULATION - your AC guys have surely seen more failures than I.

Split system air conditioner stopped working - electric wires keep burning up at the terminals

My AC split unit stop working ,because the terminal wires connecting the compressor to the capacitor always burn this happen several times ,and the remedy was to replaced the burned wires,please can you advise what the reason that keep the terminal wire burn, the compressor is newly installed, - Mohamed al lababidi -

Reply:

Mohamed,

If the terminal wires keep burning up I suspect that the problem is one of

- an overcurrent - high amps draw because a motor is seizing and needs replacement - most likely it's this problem

- bad electrical connections, possibly involving aluminum wiring or loose connectors

- improper electrical wiring - such as undersized wires for the length of run, or mis-placed connections

- abnormal voltages in the system or voltage surges

Why does a blown compressor motor burn out wires?

About compressor burn out, I have outdoor unit Daikin VRV III RXQ16PAY1 and the compressor was burned out at cable lug compressor. how can it possible happen? (sorry for bad English) 11/13/2014 Deddy

Reply:

Deddy, a failing compressor motor can draw very high current (Amps) that in turn can certainly show up at a wire connector.

This is a companion article for COMPRESSOR / CONDENSER DIAGNOSTICS.

For diagnostic questions focused specifically on the outdoor condenser unit fan or fan motor,

see FAN, COMPRESSOR / CONDENSER DIAGNOSTIC FAQs.

You may also want to see REPAIR & DIAGNOSTIC FAQs for A/C.

Question: Causes of repeated AC or heat pump compressor burn-out & circuit breaker failure

I got unit compete burn-up at the compressor unit, all the wires, contactor.

I rewired everything.

But this is the third time this has happened.

First time I believed the 30 amps breaker was defective because I could see one side was burned in the electrical panel.

Somebody put two separate breaker each 20 amps.

I replaced the two 20A breakers with a single double pole 30A breaker..

Now the 30A breaker won't open.

But the main circuit breaker tripped (opened). And I found live voltage only on one side.

So I'm only getting 120V in the place instead 240V.

I disconnected the A/C unit.

Why only would a circuit breaker open on just one side? (June 1, 2014) Voscar

Reply:

Watch out: Repeated compressor burn-out certainly means that there is another problem with the system that has not been found.

Watch out: I suspect some wiring errors or wrong circuit breaker type. When you install a double pole 30A circuit breaker in the electrical panel, an over-current can occur on either of its two 120VAC legs. In that case, an over-current on EITHER side of the double pole breaker should trip BOTH poles OFF. That's called a common internal trip circuit breaker.

In addition to the burned out compressor you have faulty, damaged, or mis-wired circuit breaker(s) that need to be replaced: tell me the circuit breaker and panel brand and I can comment further.

Watch out: But the compressor burn-up is probably not caused by the circuit breakers but by an operating problem in the system - improper charge, setup, or control board. Possibly low voltage or a start capacitor problem.

Watch out: if you are not trained in proper electrical wiring you could cause a buiding fire or be shocked or killed.

Amana RHD60A2A heat pumps keep tripping the breaker

We have a 1996 Amana HVAC system. Last summer running the AC it began popping the circuit breaker once a day or so.

Re-set and all was fine for a day until it popped again. We had service in and he replaced the condenser and at my request, installed a starter kit.

That almost ended the problem but not quite. So on a hunch, I set the electronic thermostat to wait 500 seconds before re-powering the AC after it shut off, adding about 150 seconds to the old setting.

So far, that worked. Maybe someone can explain why, and if something else needs replacing?

And maybe someone can tell me who re-builds Amana RHD60A2A heat pumps? 2020 is the last year for legal freon, and there's no way we can afford to replace this system.

We're pensioners on a shoestring. Re-build or find a less used model is all we can do. - On 2020-01-24 by Reybo -

Reply by (mod) - Amana RHD60A2A heat pump rebuild?

Reybo

What was included in "replaced the condenser" ? The whole condenser unit? That would have meant a new compressor, fan, condensing coil & controls.

So we'd not expect a new system to trip the breaker if the setup is properly wired and fused. And you'd not install a starter kit on a new AC compressor motor.

On the other hand if you're using an old compressor motor and it's tripping the breaker, a hard start kit might get it going for a time but you've already been warned that the compressor is at or near the e nd of its life.

Indeed commercial compressor motors are often re-built.

But nobody rebuilds residential A/C or heat pump compressor motors. The compressor is in a hermetically sealed can and is not repairable.

You might find a used unit but I'd be pretty reluctant to try that.

Few people will remove and salvage an old A/C or heat pump that's still working acceptably, so a used residential compressor on the market is risking having to do the job over multiple times- at a cost greater than having replaced the unit with a new one in the first place.

Heat pump trips circuit breaker

Problem is that I have an ac heat pump system with Outside condenser and Inside air handler. Once I lower the room thermostat to call for cooling (lower than the room temperature) the breaker for the unit on the main box trips and shuts down. - On 2015-06-16 by Rafael Pagan

Reply by (mod) -

Sounds like an overcurrent such as from a failing compressor or relay.

Watch out: leave power off to avoid risking a fire, then call an HVAC service tech for proper diagnosis and repair of the system.

Circuit breakers kept popping off; now the outside A/C unit won't run.

I have a Heil 10 Permence Series central air unit model NACO3OAKA1, S/N# L010404976. The 2 downstairs 30AMP breakers kept popping so i decided to clean out the unit outside.

When shopvaccing near the wires, I believe I accidently knocked a yellow wire connection loose.

To see if I did, I turned everything back on, set thermostat to kick in the air and I could hear the furnace unit kick in downstairs but the A/C unit outside wasn't doing anything (no fan, nothing).

I see one other yellow wire connected but this other one is dangling loose. Any help or would a picture help?:) On 2011-07-14 by Craig

by (mod) - how to sort out which wires go where on my AC unit

Craig:

A service tech can reconnect your wires properly, or if you are competent to handle it safely yourself you will need a wiring diagram that is either already in/on the unit or is available from the manufacturer or in the service/installation manual for your unit.