HVAC question

[DRPNGOUT]

Firstly - Hello everyone from Southern Ontario . Brand new to the RV world. Been lurking since picking up the RV end of March trying to learn as much as I can. Took it out Saturday night for the first time to a conservation area near home and had a great time.

I have a question about the HVAC. The RV has two ACs, one in the bedroom and one in the living area. There are also two thermostats, also in the bedroom and living area. The thermostat in the living area also controls the LPG furnace. Since it was cold Saturday night I set the living area thermostat to "Furnace", set the fan to "Auto" and set the temperature. What I discovered was everytime the LPG furnace would start, I could hear a relay type clicking in the living area AC clicking about 15-20 times. Then when I hear the furnace flame extinguish, the AC will click only once. It does this each and every time the LPG furnace comes on. Does anyone know what that clicking noise is?

The RV is a 2011 Georgetown 327. The thermostat is the Dometic Single Zone LCD Thermostat 3313189 (image attached) and the AC is Dometic Brisk Air 457915.

Thanks
Kim & Rick

[polkatronron]

Does your AC have a heat strip...

[grhodes50]

Or you sure it was coming from the AC and not the furnace. I know they aren't located next to each other and it should be easy to tell the difference, but I'm just wondering if you maybe hearing the furnace igniting.

[DRPNGOUT]

I believe it has a heat strip because one of the things it says on the inside label is "Heat element 1530 Watts".

I'm positive it is coming from the living area AC over head versus the furnace at floor level.

Rick

[polkatronron]

well, there has to be a control for the heat strip...I see your thermostat is electronic..take a look at the instructions for the thermostat...I bet there is a heat strip program on that thermostat and the heat strip is turned on...another way is to unplug your motorhome and run your furnace on battery...then see if the noise is still there.

[Randyman]

Hello everyone, I have a 2011 Cardinal 3425 RT and I have the exact same issue. Mine does not have the heat strip in the rear A\C and it does make the same clicking noise as described above. The furnace works great, just is annoying to hear the clicking every time it gets ready to start. Any ideas as to what is going on? It will make the same noise whether the camper is plugged in or just on battery. It is definitely coming from the rear A\C unit.

[DRPNGOUT]

I tried another test last night this time with the 5500 watt generator running and this time the AC clicked quietly only once on start and once on stop of the furnace. This seemed normal. So I retested again on battery only and again on 15 amp shore power and it worked properly both times. I can't guess what the problem was other than it was the first time I had run the furnace with the generator and the extra current finally made the relay connect?

Doing some research I am assuming now I don't have a heat strip or else they would have installed the Dometic thermostat model with the "Heat Strip" setting.

[Randyman]

We're heading out this weekend and I haven't tried running the A\C unit yet. I don't have a generator so I'll see if breaking in the A\C unit changes my situation. Still curious as to why it's doing what it is doing and that someone else has the exact same problem.

[Randyman]

Think I finally figured out the clicking relay in the rear A\C when the furnace comes on. In the thermostats instruction manual it shows that you need to "initialize" the thermostat before it's first use. I had tried that originally to no avail. While we were camped and I was getting annoyed listening to the relay clicking up to 25 times before the furnace would kick on I got the manual out again and redid the initialization as I did before. This time it must have took, no more clicking and the furnace worked great, just as it did before, minus the clicking. Hope this helps anyone else with the same issue.

[DRPNGOUT]

Is it the same Dometic Single Zone thermostat that I have? I included the picture in the first post. If so, what was the procedure to initialize.

I have noticed now that the clicking returns after a few uses which makes me think it is an electric issue. Each time I start the generator it is fine. But then after a few cycles running on 15 amp or battery it clicks again.