A/C blowing 20 amp breaker

MikePro

Member
Went out to the trailer park today to check on our trailer. I turned on the a/c and it ran for less than a minute and popped the breaker. I tried resetting it 3 or times with the same result. It was above 90F, (34C), outside today so not sure if the heat had anything to do with this because the a/c worked fine last week when is was much cooler outside. The fan works fine but as soon as I flipped the thermostat to cold the breaker would trip in about 45 seconds. This is a roof a/c unit and the trailer is a 2013 Heartland Prowler 32 foot bhs. The breaker is a 30/20 breaker with main power on the 30 side. According to specs my a/c unit should only draw 15 amps.. There is nothing else on the a/c circuit that could be drawing power.
 

Hollandt

Active Member
Went out to the trailer park today to check on our trailer. I turned on the a/c and it ran for less than a minute and popped the breaker. I tried resetting it 3 or times with the same result. It was above 90F, (34C), outside today so not sure if the heat had anything to do with this because the a/c worked fine last week when is was much cooler outside. The fan works fine but as soon as I flipped the thermostat to cold the breaker would trip in about 45 seconds. This is a roof a/c unit and the trailer is a 2013 Heartland Prowler 32 foot bhs. The breaker is a 30/20 breaker with main power on the 30 side. According to specs my a/c unit should only draw 15 amps.. There is nothing else on the a/c circuit that could be drawing power.
You really need to measure the amperage being pulled. Low voltage and/or a bad connection could drive the amperage up. Also it could be a weak breaker tripping at a lower amperage than it should.
 

wdk450

Well-known member
I agree you need to measure the AC current draw: You may have a freon leak, and the compressor then draws too much current.
 

MikePro

Member
Went out today and local temp was around 28C (82F) with a humidex of about 32C. I cleaned the unit, which wasn't very dirty at all. checked the campground voltage coming into the trailer and it was at 116v, later dropped to 107v around 5pm. I ran the a/c for about 3 hours before we had to come home and it worked fine. I did an amp draw test on the compressor common wire which in this case was the white wire and at max it was only drawing 2.7 amps. Crazy! I think the next time I go out I might move the a/c power to the 20 amp microwave breaker and move the microwave power to where breaker where the a/c was. The a/c breaker is a 30/20, main/ac and the microwave breaker is a 20/15, microwave/ground faults. Oh, and I am on my own power pedestal, not sharing with another site.
 

MikePro

Member
Sorry folks. I have to go test again. The wiring diagram on the unit was misleading. After looking up the model number I found the proper test procedure for this unit, a Coleman Airxcel model. I need to take my reading from the black wire at the compressor after it has been running on high cool for at least 30 minutes. Back to square one.
 

wdk450

Well-known member
You know, a little known fact about our circuit breaker boxes is that the breakers connect electrically to the phase buss bar with metal wedge V fingers, much like those in the Insulation Displacement Connector outlets the RV assembly lines use. I had a time a few years back where I would hear the breaker/buss bar connection arcing, along with some electrical smell. I finally took the breaker box cover off, and one-by-one disconnected the breakers (including the double mains breaker) from the buss bar system mounted in the breaker box. I found where the arcing had happened, filed the metal contact points smooth, tightened the breaker V connector to buss bar contact, and sprayed all of the breaker to buss bar contact points with Caig DeOxIt electrical contact cleaner/restorer before re-assembly. I haven't had any problems with the breaker box since.

You can get the more common sizes of our breakers at the local Home Improvement stores (including the 50 amp mains breakers); the less common size dual ones can be ordered on the internet. BTW, the air conditioning breakers have a special rating (a longer time delay trip factor I think). They are designated HACR (Heating, Air Conditioning and Refrigeration) type breakers.

Here is an E-Bay listing for the 15 amp - 20 amp HACR breaker: https://www.ebay.com/itm/185427208987?epid=169901197&hash=item2b2c52ab1b:g:pjUAAOSwrQNigmXQ
 

Hollandt

Active Member
Went out today and local temp was around 28C (82F) with a humidex of about 32C. I cleaned the unit, which wasn't very dirty at all. checked the campground voltage coming into the trailer and it was at 116v, later dropped to 107v around 5pm. I ran the a/c for about 3 hours before we had to come home and it worked fine. I did an amp draw test on the compressor common wire which in this case was the white wire and at max it was only drawing 2.7 amps. Crazy! I think the next time I go out I might move the a/c power to the 20 amp microwave breaker and move the microwave power to where breaker where the a/c was. The a/c breaker is a 30/20, main/ac and the microwave breaker is a 20/15, microwave/ground faults. Oh, and I am on my own power pedestal, not sharing with another site.
As you indicated below you need to check the wire that is actually on the breaker. Typically a black wire. The white wire should be the neutral. I am suspecting that the compressor had cycled off because the RV was at setpoint and only the fan was running. The 107 V is starting to be a concern especially if at the pedestal with no load. Typically Surge/Voltage protectors available for RV to protect the RV from bad power situations shut the power off at 102 to 104 volts. The low voltage allows the amperages to rise.
 

MikePro

Member
Thanks so much for the info. Went out to the trailer today and before opening it I checked the park voltage at our pedestal. It was 118.5 volts. I then plugged our power cable back in and checked it for a voltage drop and there was none. Went into the trailer and checked an outlet and it was at 112.5V. Probably due to indoor and outdoor fridges running and the trailer converter/generator. (Hot water tank not turned on yet) Turned the ac on cold/high and checked voltage drop at the park pedestal again and it was down to 114.5V. Left the ac running on cold/high for about 45 minutes then went up to check the compressor amperage draw, It read 15.20 amps. The Rated Load Amps rating on the ac spec tag says it should draw around11.4 amps. The unit is a Coleman Airxcel 15,000 btu and designated operating voltage is from 103.5 to 112.5 volts. With the high temp we had today I think the unit is operating just within spec and my problem may be fluctuating trailer park voltage. If so I have no idea how I can get around it other than shutting everything down except the ac on hot days when the park is full.
 

Hollandt

Active Member
Thanks so much for the info. Went out to the trailer today and before opening it I checked the park voltage at our pedestal. It was 118.5 volts. I then plugged our power cable back in and checked it for a voltage drop and there was none. Went into the trailer and checked an outlet and it was at 112.5V. Probably due to indoor and outdoor fridges running and the trailer converter/generator. (Hot water tank not turned on yet) Turned the ac on cold/high and checked voltage drop at the park pedestal again and it was down to 114.5V. Left the ac running on cold/high for about 45 minutes then went up to check the compressor amperage draw, It read 15.20 amps. The Rated Load Amps rating on the ac spec tag says it should draw around11.4 amps. The unit is a Coleman Airxcel 15,000 btu and designated operating voltage is from 103.5 to 112.5 volts. With the high temp we had today I think the unit is operating just within spec and my problem may be fluctuating trailer park voltage. If so I have no idea how I can get around it other than shutting everything down except the ac on hot days when the park is full.
I think you are on a 30 amp service based on the info above. I am on a 30 amp service also and I usually leave my HW in gas mode if running the AC because I usually get a large voltage drop some times due to the extra amp draw here. I will also leave the Fridge in Gas mode if operating on a 20 amp connection. Based on your measurement above on the "common" neutral you may also have a poor connection on the neutral somewhere in the system. This will cause the power to potentially feed through the ground and cause a larger voltage drop than normal on the system. The neutral and ground is bonded in your main panel in your home but in a RV the neutral and ground are not bonded until either at the pedestal or most likely the main panel feeding the pedestal. I would highly suggest a surge/voltage guard for you pedestal connection or installing one hard wired in the trailer. Mine recently would not allow the power to connect and the issue was a bad connection at the pedestal on the neutral connection. I had to bend the connection springs on the pedestal outlet connection to correct the problem. My AC is a Dometic 15,000, but 15 to 18 amps is not unusual for the draw when the temp is hot. I use the hardwired Progressive Industries EMS-HW30C/50C , it gives a readout of the voltage and the amps in the RV I can easily monitor. Your total amps can quickly reach the high side. AC 15-17 amps, DC convertor 3-6 amps, fridge 4-7 amps, Microwave 18-20 amps, HW (I do not remember this value but I suspect it could be 8-12 amps.

 
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