heat pump not switching to furnace

[Alumitater]

Hoping some of you will have an answer to our issue.
We have a 2007 Safari 25' FB SE with the 13,500 BTU Dometic AC/heat pump.

Our heat pump and furnace both work fine but we have noticed the heat pump setting does not switch to "furnace" automatically when the temps drop below 30 degrees.

For instance, on a recent trip we had some nights which dropped into the mid 20's and the heat pump never switched to furnace (gas). I had to do that manually.

Any suggestions?
Thanks in advance.

[dznf0g]

Anytime 12V is removed from the CCC, you must reset it for the switchover to occur. Turn the CCC off with the switch on the bottom of the unit. While holding down the top an bottom buttons on the front, turn on the switch on the bottom. You should see FFF in the screen. If so, you're set. This is in your CCC manual...but vague, IIRC.

[Alumitater]

The batteries were replaced when we purchased the trailer, so I assume the 12 volt was interrupted....so the CCC should be reset?

[dznf0g]

Yes, that's your first step.

Sent from my XT907 using Airstream Forums mobile app

[Alumitater]

Thanks, Rich, I will. By the way, my wife and I really get a kick out of your quote.......

[Alumitater]

Just an update as I diagnose this issue.
The reset on the Comfort Control Center did not cure the issue.

Checked with Dometic, they advised the unit should switch from heat pump to furnace below about 30 degrees. My problem is likely the ambient sensor (like a thermostat which tells the heat pump to switch to furnace) has failed.

I took the cover off the heat pump/AC unit on the roof and located the sensor.
I have attached a photo....it is the yellow bulb in the left center of the photo. It has a white wire which runs to a red plug and plugs into the P3 slot on the board.

Next step is to get the part number and order a replacement.
The saga continues.....