AC Short Cycling

[pappcam]

Dometic 15k AC and Dometic soft touch thermostat short cycles my AC. It comes on for about a minute and then shuts off in about a minute and repeats this. Seems specific to when the temp outside is close to the temp inside. Sometimes it's the fan only and I don't hear the compressor kick in before it shuts off again.

There is no vent pointing at the thermostat so it's not that. Hell, I'm not even sure the thermostat has the temperature sensor in it.

It's very annoying.

[TucsonJim]

Dometic 15k AC and Dometic soft touch thermostat short cycles my AC. It comes on for about a minute and then shuts off in about a minute and repeats this. Seems specific to when the temp outside is close to the temp inside. Sometimes it's the fan only and I don't hear the compressor kick in before it shuts off again.

There is no vent pointing at the thermostat so it's not that. Hell, I'm not even sure the thermostat has the temperature sensor in it.

It's very annoying.

Good morning. This is a common issue with the Dometic AC units. The temperature sensor is on the intake side of the AC. If cold air from the outlet crosses over, it will trick the sensor and thermostate into thinking that the room is at the proper temp and shut it down.

The solution is quite simple.
1. Remove the plenum on the bottom of AC.
2. Check the position of the panel between the outlet and intake side. Reposition the outlet if needed.
3. Seal up any gaps with metalized duct tape.
4. Reassemble.

Here are some photos of mine.

[pappcam]

Good morning. This is a common issue with the Dometic AC units. The temperature sensor is on the intake side of the AC. If cold air from the outlet crosses over, it will trick the sensor and thermostate into thinking that the room is at the proper temp and shut it down.

The solution is quite simple.
1. Remove the plenum on the bottom of AC.
2. Check the position of the panel between the outlet and intake side. Reposition the outlet if needed.
3. Seal up any gaps with metalized duct tape.
4. Reassemble.

Here are some photos of mine.

Thanks. This should help.

Where is the actual sensor though? At first glance it seems the two sides are pretty sealed and isolated.

[Country Campers]

I would try low fan instead of auto. If it is really hot and/or humid where you are low fan will help.

Brian

[pappcam]

I would try low fan instead of auto. If it is really hot and/or humid where you are low fan will help.

Brian

Having the fan on 24/7 is sort of noisy and annoying but I guess it's less annoying than it coming on once every 2 minutes for 30 seconds. I need to find out where the sensor is and try moving it a little or something.

Somewhat a little on topic, my Dometic thermostat is bluetooth enabled which means I should be able to control it with my phone. The app is apparently called Dometic CT or CTBT but there is no app out there for Android that I can see. Having control of this AC with my phone might make it easier to manage than with that piece of crap thermostat with cheap feeling touch controls.

[howson]

Having the fan on 24/7 is sort of noisy and annoying but I guess it's less annoying than it coming on once every 2 minutes for 30 seconds. I need to find out where the sensor is and try moving it a little or something.

Somewhat a little on topic, my Dometic thermostat is bluetooth enabled which means I should be able to control it with my phone. The app is apparently called Dometic CT or CTBT but there is no app out there for Android that I can see. Having control of this AC with my phone might make it easier to manage than with that piece of crap thermostat with cheap feeling touch controls.

Please post a pic of the thermostat--not many Dometics (that I know of) in the newer GDRVs. Most are Furrion, Airxcel (aka Coleman) with a smattering of GEs.

[pappcam]

Please post a pic of the thermostat--not many Dometics (that I know of) in the newer GDRVs. Most are Furrion, Airxcel (aka Coleman) with a smattering of GEs.

This little thing

[howson]

This little thing

First time I've seen that model. A search turned up it's a Model 9600023355 ( https://www.dometic.com/en-us/outdoo...rmostat-217175 )

I found the manual at https://epi.dometic.com/externalasse...7113_64643.pdf

You're right about the Dometic app -- only reference I found doing a DuckDuckGo search that returned https://play.google.com/store/apps/d....outdoor&pli=1 However, searching on the Play Store (on my phone) didn't result in finding the app. Searched again on DuckDuckGo (on my phone) and found three apps but none of them are for the thermostat. The reviews for the three apps that are there are miserable -- folks have no luck connecting to their devices. Bottom line: ignore the bluetooth option (at least for now) as it appears to me that's it's not an implemented feature due to lack of app support.

To determine if the thermostat has a temp sensor, point a hair dryer at it and monitor the display. Does the temp rise? If not, the sensor may be in the plenum as was the case for the Furrion. See https://gdrvowners.com/forum/operati...ssue-yes-again for the story on that issue.

Howard

[pappcam]

First time I've seen that model. A search turned up it's a Model 9600023355 ( https://www.dometic.com/en-us/outdoo...rmostat-217175 )

I found the manual at https://epi.dometic.com/externalasse...7113_64643.pdf

You're right about the Dometic app -- only reference I found doing a DuckDuckGo search that returned https://play.google.com/store/apps/d....outdoor&pli=1 However, searching on the Play Store (on my phone) didn't result in finding the app. Searched again on DuckDuckGo (on my phone) and found three apps but none of them are for the thermostat. The reviews for the three apps that are there are miserable -- folks have no luck connecting to their devices. Bottom line: ignore the bluetooth option (at least for now) as it appears to me that's it's not an implemented feature due to lack of app support.

To determine if the thermostat has a temp sensor, point a hair dryer at it and monitor the display. Does the temp rise? If not, the sensor may be in the plenum as was the case for the Furrion. See https://gdrvowners.com/forum/operati...ssue-yes-again for the story on that issue.

Howard

Awesome. Thanks for all that info. I've been told the sensor is in the plenum so I made sure there were no big air gaps between the cold and return sides on the plenum and other than two small screw holes I covered with tape, it seemed to be sealed tight from the factory. I've resorted to just leaving the fan on low all the time when cooling for now until I get back home. Unfortunately I don't have a 30 amp or 50 amp hook up for my trailer at home to troubleshoot it. I'd like to move the sensor if possible at the very least.

[howson]

pappcam -- when you do resolve this issue, please come back and document the resolution . The power of this owners' forum is the sharing of our experiences. (TIA!)

[Jlawles2]

howson Howard, Parts lookup shows it to be a Brisk II by Dometic.

pappcam Keep your eye on that unit, unfortunately I replace 2 of them since 2014. The first one was a 2014 model and it was replaced 25 months after purchase of the unit, the second was a 2020 and it was replaced 18 months after purchase of the unit. They seem to have a track record for the capillary tubes plugging up causing them to stop cooling. Also they are "non repairable" by the MFG but if you or someone you know does refrigeration work, they can put in service valves and an adjustable orifice if the unit fails and never have issues again.

The app is still available in the apple app store it's called Thermostat Control by Lifestyle. Has not been updated in 5 years (about normal for the RV industry).

[pappcam]

Thought I'd update this thread. I replaced that little crappy Dometic thermostat with a Micro-Air EasyTouch thermostat and the issue has gone away. Sucks that I needed to replace the thermostat on a new RV but the new thermostat is 100x better anyway.

[TucsonJim]

Thanks for the update Papp.

Jim