central ac question

[automech]

I have a 10 + year old trane ac/heat pump unit that is blowing the 40 amp breaker about once a day, midday usually. I leave for work, it's blowing cold. Come home, its not running, breaker tripped. Re set breaker, blows cold all night. Next day same thing. I had the ac guys come out, and they sold me the start capaciter and relay. 500 dollars and 3 weeks later the same thing is happening. I call them up again, they come out and now they say there is nothing wrong, and I should call an electrician to see if I can get a 50 amp breaker installed. They say the unit calls for a 40 to 50 amp breaker. I don't know if the wires to the unit are sized for a 50 amp breaker or not, that is what the electrician will look at. I am in the auto repair business, so I can kinda feel that the guy maybe guessed wrong at the starting parts, but I am not an HVAC expert. Right now I kinda think I need a new compressor or entire assy. since it ran fine for 10 years without tripping the breaker. Does a bigger breaker sound reasonable? I am thinking the compressor is getting old and need more amps at startup, maybe it's drawing 45 on a hot day or something. Any advice on my next step? If I need a new unit, I am going to ask that I get some money back from what I think is a bum repair.

 

[sandman2234]

I also am thinking you got hosed on the capacitor and relay. Those parts just don't cost that much. Mom's run capacitor went out last week on a 3.5 ton unit and the capacitor was $7. Didn't have to replace the relay, but still, that part while more than a capacitor still isn't that much. Mom's total bill was less than $50 which is typically less than a service call.
My 4 ton unit showed the same non start patterns that my Mom's did, and I called the same company. The same tech cost me $75 for a service call and my 12 or more year old is still dead. Compressor appears to be the problem. I can tell you that anybody that says it is hot, is correct. I will make a decision on just how much to spend to make my wife a happy camper tomorrow most likely. The 1.5 ton unit I have running temporary has bought me a little time, but it isn't holding it's own in this heat, just making it bearable.(and that is debatable, lol)
David from jax

 

[tallyho8]

The most common cause of a problem like yours is dirty condenser coils but that is usually the first thing a serviceman checks so it may not be your problem.

A unit will pull too many amps if any of the wires or wire terminals are corroded. A circuit breaker will overheat and click off if it has dirty terminals or a loose wire connection. Circuit breakers do also fail at times and if you change breakers it would be best to try a new 40 amp instead of putting in a 50.

Too much refrigerant in a unit will make it pull too many amps on a hot day. A thermostat that tries to restart the unit too soon will cause a tripped breaker.

I've installed many hard start kits (start relay and capacitor) in units for $75 so your repair seems very high.

 

[dex3361]

I would check the amp draw off of the breaker that is tripping. You can check the amps against the chart that the manufacturer publishes but it would be in the 11 amp range running for the outdoor unit(all depends on the brand, temp inside and out, humidity and airflow). It is not unusual for a breaker to get weak and trip. The hot weather increases the amp draw of the unit several amps and could be pushing the weak breaker over the edge. The 240V breaker would cost maybe 30 dollars or less depending where you buy it.

 

[Transit]

At startup the compressor is in a LOCKED rotor condition and will draw up near 80-90 amp surge. As the compressor comes up to speed the current will go down to 8 to 10 amps.

Your T-stat should have a device built in that will keep the AC from coming on a gain for a bout 3-4 minutes if the unit has been running. This time delay allows the pressure to equalize in the unit so the compressor need not push against a large load. You could try running the AC, stop it and turn it on again, that will test the time delay if you have one.

 

[milkman636]

The most common cause of a problem like yours is dirty condenser coils but that is usually the first thing a serviceman checks so it may not be your problem.

A unit will pull too many amps if any of the wires or wire terminals are corroded. A circuit breaker will overheat and click off if it has dirty terminals or a loose wire connection. Circuit breakers do also fail at times and if you change breakers it would be best to try a new 40 amp instead of putting in a 50.

Too much refrigerant in a unit will make it pull too many amps on a hot day. A thermostat that tries to restart the unit too soon will cause a tripped breaker.

I've installed many hard start kits (start relay and capacitor) in units for $75 so your repair seems very high.

Good advice here.

Clean the condenser. Check wire connections at panel, service disconnect, and contactor. Put a clamp on ammeter on each lead when it it is running and see what the amp draw is. If it is less than the FLA rating on the name plate with a clean coil and good connections and still tripping the breaker, then the breaker needs replacement.

A decent service tech should have taken these steps when he was there, and taken a few minutes to explain what he checked and why he replaced what he did.

 

[Dennisfly]

I have a 6 year old Trane that is doing the same thing. I've checked/cleaned/tightened all the high voltage wire connections, cleaned the coil, and replaced the circuit breaker. I called the company that installed it and they checked the amp draw, resistance, connections, relay, capacitor, freon charge, air temp drop, Tightened connections at the breaker panel, and said everything is in spec.

I talked to my brother who is an air conditioning contractor, but located on the other side of the country, and he suggested that I install a "start kit" which is an additional capacitor for starting and will lower the starting amp draw. I installed it and it made no difference. By the way, it only cost about $20 and I installed it myself in 30 minutes.

Of course, it only does this once or twice a day, and never while the serviceman was here.

My brother suggests that it may be the compressor about to go bad, but after testing OK, and only being 6 years old (five year warrantee!) I don't want to just start arbitrarily changing expensive parts.

Mine is a 40 amp circuit and my brother says the electricians always seem to put in the minimum amp breaaker while the HVAC guys would like the maximum Like Automech, I would like to increase the breaker amp capacity but not if it exceeds the limits of the wire. Does anyone know the required wire gauge for 40 amps verses the next breaker size up (is that 50 amps?)?

 

[brin]

We just had one of our heat pumps start blowing hot air, it is a GMC and is 6 yrs. old. I called the AC guy and it was a capacitor...He was here for about 30 minutes and the bill was $160.00 and everything works fine now....I think your guy is high.

 

[Argosy]

Along with checking the current check the voltage. It's been a hot year, lots of ac systems working overtime and drawing a lot of power. As voltage drops current will increase.

If the breaker is older it will trip easier, might not hurt to replace that either.

 

[Chuck52]

Since it only trips during the day, is it possible your power company is reducing the voltage during peak demand times?

Chuck