A/C Compressor Cycling on/off and Blowing Breaker

[Griswald One]

Good Day All,

For the last two nights our A/C has repeatedly blown the breaker in our Greyhawk. At first I thought there might be an issue with the shore power, but now I am not so sure.

I listened to it last night before the last time it blew and I could hear what I think was the compressor cycling on and off. There were three distinct sounds. First was what I would call the regular fan sound. Second was a deeper fan sound, as if under greater load and finally the humming sound that I assume is the compressor. The compressor would run for 10-15 seconds and then shut off. It cycled about 6 times before the breaker popped.

We had the temperature set fairly low, 69. My DW likes it cool and the thermostat is less then accurate. We have to set it that low to get it down to 72ish in the bedroom. The temp at the thermostat was at 69 when the breaker went.

The odd thing was, after the last time the breaker went I bumped the temp up to 72 just to give the A/C a break. When the unit next came on it worked perfectly and shut down again when the temp was reached without going through the cycle described above.

Of note the A/C has been working perfectly through 9 days of full sun at Myrtle Beach and ran fine yesterday in the heat in PA. The only time this has occured is at night when the A/C is not struggling to reach the desired temp.

Any suggestions as to what the problem might be is appreciated.

[The Turners]

It could be a capacitor is bad. Get checked out before you burn up the motor.

[Shakedown St.]

Based on your description, it sounds like the compressor was shutting down on a low pressure safety switch. When the evaporator gets too cold, for whatever reason, the refrigerant pressure drops. When the compressor "short cycles", it draws very high amperage on startup. This may have been causing your breaker to trip. Check that your filter is clean, and make sure you are running the fan speed on high. A dirty filter will cause a restriction of air at the evaporator, thus making it colder. Low fan speed may not move enough air across the evaporator. Possibly even a refrigerant leak, which would not be good.

It's possible to be short cycling on high head pressure too, but when you say you raised the tstat temp and it ran ok the latter seems more likely.

It could be electrical too, but a bad compressor capacitor usually will not allow a start up, without tripping the breaker.

Also possible there was a temporary drop in voltage at the post, which may cause this condition. Just a few things to think about.....good luck!

[Griswald One]

Thanks Guys, Voltage drop at post was my first suspicion. But the cycling I heard led me to think it may have been another source.

I followed up on Shakedown's suggestions, since they were fixes I could do. The fan speed was on low so flip of the switch and that was solved. The filters were probably 30% blocked, suprised me for a new rig... But it did sit on the lot for several months and we have been on board about 30 days. They are now clean.

We did have quite a bit of condensation on the A/C while we were in SC, not sure if that would have added to our issues, other then the dust in the filters was damp which would reduce airflow even further.