AC came on while the furnace was running

kcamp99186 · 09-29-2015, 04:23 PM

We have a Premier 30RIPR and while camping last weekend we ran our furnace. I then started our generator and the AC came on while the furnace was actually running. The thermostat was on heat. Switched off the breaker to turn off AC. Any ideas what could cause this?

**chuckster57** · 09-29-2015, 04:35 PM

Sounds like you have the square dometic digital thermostat. When you press the button to activate the fan, you have three choices.

Au: Automatic. In this mode the fan only comes on when the A/C compressor comes on to cool the coach.

Hi/Lo: when either one of these is chosen, the fan will run continuously when the A/C is chosen and the compressor will cycle on/off depending on temp setting. In this setting the A/C fan will run on the selected speed when the furnace is selected.

To change the fan options, press the bottom button until the fan LED lights. Then using the temp up or down cycle thru to the desired setting. If you DONT want the A/C fan to run when you use the furnace choose Au (automatic). This only applies when you have 110VAC supplied to the trailer. If your not plugged in to any 110 power source, the fan wont run as it is an AC current fan.

All of this should have been explained in your walkthrough/orientation. It never ceases to amaze me how many employees doing them don't know and don't ask.

mcsearch1 · 09-29-2015, 04:58 PM

Chuckster is absolutely correct. I experienced the same thing in my Passport on the first time out in May this year. When the fan is not in AU it will come on while the furnace is running.

GaryWT · 09-29-2015, 05:46 PM

As others said, fan was on. I have not tried this but some say once the air warms up the fan will help the warm air move around.

**chuckster57** · 09-29-2015, 05:53 PM

Quote:

Originally Posted by GaryWT

As others said, fan was on. I have not tried this but some say once the air warms up the fan will help the warm air move around.

I took an 8 hr. Training course last week given by a dometic rep. That is exactly the reason he said it was set up this way, to help circulate the air since warm air rises.

kcamp99186 · 10-04-2015, 06:39 AM

Thanks so much for your help. Definitely was not gone over in our walk thru.

jje1960 · 10-04-2015, 07:40 AM

Once you understand why it's doing it (we went through same) the option is very useful, it really spreads the cabin heat around pretty quickly. I used it yesterday as a matter of fact...

theeyres · 10-04-2015, 08:42 PM

Yes, the AC didn't come on but the A/C fan did...to circulate the air.

You may also like: