AC turns on while control is off

We were staying in Washington State Jan and Feb, outside temp was in the 20s and 30s, I had the furnace running day and night with no problems on a 50amp hookup. When we moved to the KOA camp all they had was 30amp and that's when the problem started. Outside temp 48, furnace on, and AC tried to come on, the only way I could keep the AC off was to pull the breaker. Turned heat off and turned on the AC breaker and the AC tried to start so I now have the breaker off, seams to be a problem with the 30amp service.

Anyone run into this or have any idea how to fix it?


Thanks

Bryan,
Could it be that what you are interpreting to be the "AC" is really the Heat Pump trying to come on. Not sure if you have that option on yours, but that would be my guess. If you have the HP option, let it come on and see if you may have some warmth coming out of the vents. If you don't have the HP option, make sure you have the thermostat for the AC set high. Good Luck.

Bryan, try this from another thread:
If you have the Dometic Single Zone LCD Thermostat, you may have the Fan set to High or Low, rather than on Auto. Cycle the thermostat from Heat to Fan mode and use the +/- buttons to change the setting to AUTO.

Squatty said:

Bryan, try this from another thread:
If you have the Dometic Single Zone LCD Thermostat, you may have the Fan set to High or Low, rather than on Auto. Cycle the thermostat from Heat to Fan mode and use the +/- buttons to change the setting to AUTO.

Click to expand...

This would be my bet on the problem. This happen to me when I first got my unit.

Hi folks, thanks for the response

We do not have a heat pump, and we have the old single zone Thermostat, not the new LCD one. We keep the fan on auto, and with the temp in the low 40s we were only running the furnace, the AC was turned off and like I said, the problem did not show up till we went to 30amp service. Thinking about taking the unit into the repair shop to see whats wrong.

Bryan,

It's hard to see how to make a connection between changing to 30amp service and the A/C starting on its own.

The thermostat connects to a relay box that's usually above the A/C return air vent. When the thermostat calls for heat, or for cooling, it's sending 12V signals to that relay box. In HEAT mode, it sends power to the furnace. In COOL mode, it turns on power to the A/C compressor. The A/C fan is powered continuosly when the thermostat Fan setting is on HIGH or LOW.

If you're sure the A/C compressor is running (not just the A/C fan), something is causing the relay to be energized when it's not supposed to be. If it's the fan only, with the Fan setting on AUTO, something is causing that circuit to be energized.

I would take the cover off the thermostat and see if you have wires that are loose, broken, or shorted.

Thanks Dan, I'll take a look for broken wires.

Are you sure its not the fan that is staying on? It fooled us when we accidentally turned it one the first time. If you turn that on then go past it and turn the heat and AC off the fan will keep running. Go back into the fan mode and turn it off by using the arrows