Master Bedroom AC Cycling On and Off

[Devin4242]

We have a 2016 Momentum 327M. Turning on the main living HVAC, no problems. But if we turn on the one in the master bedroom, it starts and runs fine, but once the thermo set temp is reached and it shuts off, it will continue to turn on and off, sometimes within a 5 or 10 minute period repeatedly. My experience with HVAC units in general indicates repeated cycling is not good for the compressor. Is there something I'm doing wrong? Should I just let the main unit cool for most climates until it's really flippin' hot? Or is there something wrong with the thermostat on this brand new, state of the art, super camper? Thanks in advance for the forum member input.

Devin

[LCBoyer]

Can you tell if cold air is blowing on temperature sensor? If so, maybe you can turn vent

[Second Chance]

There are two things that may be going on here (and this has been posted and answered several times on the forum). RV ACs have two-speed fans. When the room temp approaches the set temp, the AC will shut down the fan momentarily and switch from high speed to low speed. As often as not, it will figure out that low speed isn't going to cut it and do the same thing to cycle back to high speed. If this is the case, you can just go to fan mode, set the fan to "High" (full-time mode) and change the thermostat back to "Cool." The fan will run continuously on high and the compressor will cycle on and off. This situation is very common and the compressor continues to run while the fan is switching off to change speeds.

In our case, we had a bad relay on the controller board on the front (bedroom low-profile) AC. The AC would run until the room hit the set temp, cycle off, and not come back on. Replacing the controller board in the AC fixed this problem.

Rob

[C&H Conner]

Rob nailed it. Don't set it on "Auto" or it will cycle continuously. We keep the fan set to "high" all the time but only really use the front A/c to blast cool the bedroom when needed. The main A/C sends enough cool air up there to keep it tolerably cool unless it is above 90 outside.

[arhayes]

Actually, we've full-timed in our 3 Dometic AC rig for over 2 years and have never experienced this. If I have the units set to "cool" and the fan set to "auto", they have functioned just like our central AC in the S&B did and only cycle on/off as needed. I do hear the compressor kick on after the fan begins, and cut off at the end of the cooling cycle. We do not have heat pump units....could that be the difference?


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[Second Chance]

Actually, we've full-timed in our 3 Dometic AC rig for over 2 years and have never experienced this. If I have the units set to "cool" and the fan set to "auto", they have functioned just like our central AC in the S&B did and only cycle on/off as needed. I do hear the compressor kick on after the fan begins, and cut off at the end of the cooling cycle. We do not have heat pump units....could that be the difference?


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We don't have heat pump units, either, Alan. The behavior described is not uncommon... I guess you're just lucky!

Rob

[Devin4242]

Sorry this response is so late, but thank you all for chiming in. I have found that, as C&H Conner pointed out, the main AC unit does adequate cooling for the whole rig, and I only turn the bedroom unit on when getting set up in the summer heat, or after coming home after a long day and want to "chill out" in the bedroom. Also after getting out of the shower and needing to freeze dry a bit. I will also try just turning on the fan to keep air circulating in the master, which is really the issue - moving air is so much more pleasant than stock still air.

On another note, it would be nice if there were a way to ventilate the master with fresh air from the outside, not having a window with screen in the master (only the emergency exit window. I wish that one had the ability to open for refreshment AND be an emergency window.

I've got a 3 week stint for work in December down in Houston coming up. Who knows what the weather will bring down there!

Cheers,
Devin

[Rclbud]

Our emergency windows open... just pick up the red handle a bit, swing to center and push out. And they have screens.

[Devin4242]

Rclbud, never thought to check, just figured they were for breakout only. I'll check when I get down to Houston. Thanks for responding!

[TucsonJim]

This thread is a good reminder for everyone. Make sure you open your fire escape windows at least twice a year. It will keep the gasket from sticking to the window frame which will make it difficult to open. Also everyone should know how to open the emergency windows and that you should place clothing, a bedspread or pillow on the frame if you have to crawl out. That will keep you from cutting yourself on the metal.

Jim