Dometic AC issue

[shepardmike]

Well this trip has been interesting. The front A/C unit ran all night last night. The outside temp was 67 and the thermostat was set to 74. When I woke up I turn it off from the precision panel and the fan shut off but the compressor kept running. When the compressor finally shut off (maybe 10 mins later) water started pouring down from the intake vent over the dinette. I have also noticed that every once in a while the vents are pumping out heat like the heat pump is running. It does that for about a minute and then cold air comes back.
2019 34QS

I would like to figure this out before calling the dealer.

Thermostat? Coils icing over?

Any thoughts?

[SeaDog]

The heat before cool air may be a delay in the reversing valve not a problem. The water coming from the vents sort of indicates ice over coils which can be caused by dirty filters or low charge. Why the compressor would continue after the fan has shut down seems to indicate a faulty contactor just a guess

[shepardmike]

Weird about the compressor. I woke up this morning and just the compressor was running again. I turned the front unit completely off with the breaker. Let it sit like that for an hour. I didn't realize the rear AC was plumbed to the front vents. So I have a little cooling coming from the rear. Every now and then the front compressor comes on (without the fan) and runs for a few minutes then shuts off. Gremlins

[red0801]

Originally Posted by shepardmike

I have also noticed that every once in a while the vents are pumping out heat like the heat pump is running. It does that for about a minute and then cold air comes back.

This is normal operation caused by 1 or 2 different control features:

1st instance - After 2018, all Berkshire units were equipped with an integrated evaporator thermostat in the Front AC unit. This thermostat senses evaporator temp to prevent icing. It will turn Off the compressor when the evap reaches approx. 30 degrees & resume operation when the fins return to temps above 50 degrees.

2nd instance - The PrecPlex, Energy Management System will turn off the compressor once the desired interior temperature is achieved. If the fan selection is set to LOW or HIGH the fans will continue to run. This can be eliminated by selecting AUTO for fan speed, with Auto selected the fans will run for 2 minutes after the compressor then turn off as well. Please note that if either the Living Room or Bedroom fan is set to Low/High, it will continue to run until the AC or Heat is turned OFF entirely.

If this is a concern, AC operation software for the Touchscreen has been upgraded. You can get those upgrades by contacting Tech Support @ Precision Circuits:

Technical Support
Precision Circuits Inc
2538 Wisconsin Avenue
Downers Grove, IL 60515
630-515-9100 EXT-704
Email:
tech@precisioncircuitsinc.com

Originally Posted by shepardmike

When I woke up I turn it off from the precision panel and the fan shut off but the compressor kept running.

The compressor should NOT continue to run after the fan is OFF & should be addressed ASAP. I would suggest contacting Forest River Tech Support.

Mike Winterrowd
Warranty Plant 40
(574)296-9641
MWinterrowd@forestriverinc.com

[shepardmike]

Thanks Mike, will do!

[shepardmike]

So I contacted FR and Precision. Consensus is I need a new touch panel. There have been changes in the firmware specific to the AC operations. If that doesn't fix then I need to install the tube style freeze sensor.

[shepardmike]

The new Precision Panel didn't fix the freezing issue so I went back to FR for new parts. Thank you @red0801 for identifying the correct parts. Whether it fixes the issue remains to be seen. I need to get it out under the hot sun again and test. The Living Room thermostat was rusted. It sits just inside the lower fiberglass lip. Is there anyway to prevent this from getting moisture? Would it hurt to wrap in ziplock bag?

What I didn't get was the rear AC (Penguin II with no heat pump) freeze sensor shown in Pic 1. I included pics for other to see in case you run into this issue. I will do the same on the FR Facebook page. Pic 2 is where FR modified the AC to interface with the Precision Panel. Pic 3 is the rusted thermostat and Pic 4 is the part # and cable set.

[red0801]

Originally Posted by shepardmike

What I didn't get was the rear AC (Penguin II with no heat pump) freeze sensor shown in Pic 1. I included pics for other to see in case you run into this issue. I will do the same on the FR Facebook page. Pic 2 is where FR modified the AC to interface with the Precision Panel. Pic 3 is the rusted thermostat and Pic 4 is the part # and cable set.

Glad to help. In regards to the different style freeze sensors. Dometic supplies the diaphragm style freeze sensor for their Standard Penguin II units. This style freeze sensor is not ideal for a heat pump application due to its limited ability to withstand direct heat. So FR sourced a more applicable freeze sensor.

[shepardmike]

@red0801 - Update#3 During the last trip the rear AC couldn't keep up and ran and ran and ran. I had both AC’s running in the driveway yesterday while I was cleaning the inside after the trip. They were both draining (dripping) down like normal while the puddle was bigger on the front. When I finished I shut them both off and closed up the slides. I noticed the front stopped dripping within 5 mins and the rear continued to drip for another hour and 20min. That indicates to me that there was some icing going on up there even though there was some dripping. I ordered the freeze sensor show in Pic 1 and my question is location. Does that look like the correct location? Shoyuld it be more in the middle, higher/lower??

[Maingler]

Couple of inches from the bottom is best. I try to clip it on the second copper line from the bottom.