A/C tripping breaker - Think this was the problem?

LeeH · 09-12-2010, 10:32 AM

Our A/C compressor started tripping the breaker a couple of days ago. I hope this crispy contactor was the problem. Think this was enough to cause the breaker to trip?

MBAtarga · 09-12-2010, 11:25 AM

that would make sense

A930Rocket · 09-12-2010, 11:27 AM

Yep...

Green 912 · 09-12-2010, 01:03 PM

Might just be a symptom of the real problem. Overload will fry the contacts. Check the start (inrush) and run amps of the compressor and condenser fan also check the capacitors on the condenser fan and compressor.

MarKoBrow · 09-12-2010, 01:13 PM

I would immediately check the capacitor first than the condition of the compressor and the charge make sure there is no blockage that contactor looks as though the compressor is working against a high side blockage. Replace the relay and the problem will only go away temporarily

LeeH · 09-12-2010, 01:47 PM

A little more info... the condensor fan (15 year old original) went out a month or so ago. It and its capacitor were replaced by an independent a/c guy who checked out everything when he was here. The compressor and run capacitor were replaced about 6-7 years ago. But again, both of those checked out a few weeks ago.

rick-l · 09-12-2010, 04:14 PM

Is that the relay in the condenser? If so I'd start saving for a new unit.

Icemaster · Icemaster's Garage

Quote:

Originally Posted by rick-l

Is that the relay in the condenser? If so I'd start saving for a new unit.

Ditto.

Overload usually means your compressor is about to die. Drawing more amperage than the breaker can handle on startup.

What does "checked out" mean? I don't think there's a check to see how much life is left in a compressor, more just checks to see if there's refrigerant in and how much amps it's drawing when running.

Check the power leads going to the compressor itself, especially the connections. If you see evidence of the same crispiness, bite the bullet and schedule the replacement.

futuresoptions · 09-12-2010, 05:17 PM

One of two things... the guy that came out does not know how to do a proper PM, or the compressor is starting to pull more amps recently maybe due to internal problems as a bad bearing... I would guess the first... A new contactor is the cheapest way to go at this point.. if the new contactor goes out pretty quick you know you got other problems... +1000 on checking your LRA (Locked rotor amperage (Startup) and your FLA (Running amperage) anything 10% above name plate shows possible internal problems... be careful when checking though..... also if you are starting a unit where the inside of the house is very hot it can give you higher than normal readings as well... hope this helps...

futuresoptions · 09-12-2010, 05:46 PM

Oh BTW, you know when a breaker trips under load that it looses approximately 10% of its effective rating right???? So when a 30amp breaker trips under load it comes close to being a 27amp breaker and so on....

Chocaholic · 09-13-2010, 06:44 AM

Had a breaker throw on ours when we bought the house. Seems coils were just caked with dirt and grime, apparently causing overheating. Once completely cleaned...system worked great for the rest of the summer without issue. Just a thought and easy to try.

javadog · 09-13-2010, 10:02 AM

Check your line voltage, too. We have sags from the power company from time to time and I've seen voltages as low as 200, or less. Ees Not so bueno, if you have low voltage when your system is trying to start up.

Also used to see contactors burn up early in systems that were really oversized and that cycled a lot.

Then, there's the new "parts from China" problem...

JR

LeeH · 09-13-2010, 02:31 PM

Quote:

Originally Posted by javadog

Also used to see contactors burn up early in systems that were really oversized and that cycled a lot.

Being AZ, it definitely cycles a lot.

I'm going to take a wait and see approach to this. I've had two friends who had older but working systems replaced recently as they were sold on the idea that they'd save money on utilities. Both regretted it later when their power bills actually went up!

LeeH · 09-25-2010, 03:53 PM

I've done all I can do... new contactor, breaker, capacitor, and added a hard start kit. Still tripping in the heat of the afternoon. Had the independent A/C guy back out. Pressure's good. Draw while running is good. At this point I'm guessing it's time for a compressor.

Any other suggestions before we go down that road?

futuresoptions · 09-25-2010, 05:56 PM

Did you check your amps/pressures during the hot part of the day?

Does this thing have a high pressure cut out that does not have a manual reset?

Could your condensor fan be shutting off intermittently?

Can you check compressor temps with infrared thermometer during running?

There may be a short in your low voltage wiring that causes the unit to bump on and off... this will cause the unit to try and start against high head pressure... weedeaters and corrosion are two factors... t-stat failing could do the same thing...

If your pressures and temps are reading good, this is what I would look at before replacing the compressor....

LeeH · 09-25-2010, 06:27 PM

Quote:

Originally Posted by futuresoptions

Did you check your amps/pressures during the hot part of the day?

Does this thing have a high pressure cut out that does not have a manual reset?

Could your condensor fan be shutting off intermittently?

Can you check compressor temps with infrared thermometer during running?

There may be a short in your low voltage wiring that causes the unit to bump on and off... this will cause the unit to try and start against high head pressure... weedeaters and corrosion are two factors... t-stat failing could do the same thing...

If your pressures and temps are reading good, this is what I would look at before replacing the compressor....

Condensor fan & relay were just replaced. It's not cutting out. Yes, the a/c guy was out at the hottest part of the day. He was a bit baffled as the pressure was good - he said he was assuming that he was going to find it overcharged. Comressor doesn't seem to be cycling in any unusual way. The unit sits right outside our kitchen window so it's easy to keep tabs on what it's doing. The only thing we hadn't tried was to hose down the coils, which we did today. Being AZ, they were pretty dusty, but not gunked up.

futuresoptions · 09-25-2010, 06:34 PM

Yeah, I have seen low voltage wiring where only the insulation was holding the wire up... it will cause the compressor to cut out and then will try to immediately restart it.. (shorting out) if your unit does not have a 5min time delay outside I would install one, tstat could be on the fritz too... hard to say without being there to look and see what you have...

turbo6bar · 09-26-2010, 01:11 PM

Your tech needs to measure amperage. Ohm out the compressor to get insight about condition.

Until you can isolate the problem to the condensing unit, I would not replace it.

What was the techs recommendation?

The suggestion to add an on-delay relay is good. This would eliminate issues with thermostat or low voltage wiring and isolate problems to the unit.

If the compressor does require a hard start cap, then your compressor could be going. Again, check start and run amperage, compressor terminals, and ohms.

This is just fishing.
good luck,
jurgen

turbo6bar · 09-26-2010, 01:13 PM

BTW, if your low voltage wiring was bad and caused the contactor to step in and out, your contacts would be burnt out in short time.

LeeH · 06-04-2011, 08:56 PM

Sigh... here we go again. My compressor is back to popping the breaker. Had another check via the power company and they also said the draw was low. I did end up installing the hard start capacitor last year and a new breaker. Not sure where else to turn.

I'm not familiar with the delay relay. Is that easy to find/install? We're just getting started with the hot months here. I need to get this thing sorted out.