Another AC Question - Montana Owners Club

Baldicon · 07-17-2018, 09:24 AM

Brought home a new 3121RL a month ago, and have been camping in it since. One odd thing that I have noticed is that randomly, the AC fan will cut off for maybe 5 seconds and then start back up and will run for several seconds and repeat several times. I have watched my Progressive Industries amp meter and it shows the compressor still running. And, the compressor overload would not let it start back up with just being off a few seconds (pressures have to equalize). This is happening in both our bedroom AC and the living area heat pump. It usually does it after it has been running for a while. Doesn't do it all the time. No complaints about the trailer is staying cool, and there seems to be good air flow. Any one else experienced this? I know some have experienced restricted air flow issues, but I don't think that's the case here.

**AZ Traveler** · 07-17-2018, 11:48 AM

Baldicon,

I tend to run my a/c on high fan vice auto to prevent this issue.

Ram Montana High Country · 07-17-2018, 03:30 PM

Sounds like some sort of heat issue in the AC but yet the Tstat isn't satisfied yet and tries to keep it running

**DQDick** · 07-17-2018, 05:00 PM

The opposite could also be true. The feeze sensor could be in the wrong position (ours was on one) and sending a signal to shut down before it should.

Baldicon · 07-17-2018, 05:27 PM

Would either the heat issue or cold issue shut just the fan down and leave the compressor running?

masterdrago · 07-21-2018, 01:01 PM

Ours does exactly the same thing as yours Baldicon. Nowhere have I found a satisfactory explanation. I've just decided that it does not matter since the compressor is not cycling. Probably a thermostat thing.

Baldicon · 07-21-2018, 01:08 PM

Quote:

Originally Posted by masterdrago

Ours does exactly the same thing as yours Baldicon. Nowhere have I found a satisfactory explanation. I've just decided that it does not matter since the compressor is not cycling. Probably a thermostat thing.

We've just had our trailer for month, and it's already getting to me. I can't stand not knowing what's going on. Also makes me wonder about the life of the motor. Sorry you're having the same problem. I'm suspecting something in the thermostat too. Someone mentioned a freeze switch, but I would think that would shut the compressor off and keep the fan running to melt the ice.

RoadRunnerTR21 · 07-21-2018, 02:15 PM

Ours does the exact same thing. We really noticed it when we were in Catherine's Landing in Hot Springs 2 weeks ago. It was really hot that week unless the storms pop up.

mtlakejim · 07-22-2018, 08:07 AM

Quote:

Originally Posted by RoadRunnerTR21

Ours does the exact same thing. We really noticed it when we were in Catherine's Landing in Hot Springs 2 weeks ago. It was really hot that week unless the storms pop up.

How did you like Catherine’s Landing?

Baldicon · 07-21-2018, 02:58 PM

masterdrago and RoadRunnerTR21, do both units in your trailer cycle off/on? Both in mine do.

masterdrago · 07-21-2018, 05:44 PM

Quote:

Originally Posted by Baldicon

masterdrago and RoadRunnerTR21, do both units in your trailer cycle off/on? Both in mine do.

Yes. I find that the bedroom is much more effected by this issue than the living room. I had originally thought it might be air from one of the ceiling registers blowing air on the stat. Found that was not the issue. It goes through spurts of doing it and I've not been able to pin down the pattern.

I did see someone way back mention that it might be warm air migrating up into the space behind the stats. They used foam behind stat to try a fix. I still don't know how to get the stat off the wall to check that. It seems like an easy experiment to try.

Baldicon · 07-21-2018, 08:03 PM

Quote:

Originally Posted by masterdrago

Yes. I find that the bedroom is much more effected by this issue than the living room. I had originally thought it might be air from one of the ceiling registers blowing air on the stat. Found that was not the issue. It goes through spurts of doing it and I've not been able to pin down the pattern.

I did see someone way back mention that it might be warm air migrating up into the space behind the stats. They used foam behind stat to try a fix. I still don't know how to get the stat off the wall to check that. It seems like an easy experiment to try.

Same here, they both may run fine all day, and then just start acting up. I don't think warm air behind the thermostat would cause this since the compressor continues to run. But maybe the thermostat is smart enough to change fan speeds based on temperature while the compressor continues to run. But warm from the wall will make the thermostat not sense the room temperature like it should.

Kent Carter · 07-25-2018, 02:55 PM

Count me in! Mine does the same thing and the bedroom ac does it more often. Keystone c/s said it was normal.

This past weekend at about 2 in the am, the one in the bedroom came on for a few seconds and went off. It did this about four times before I had enough and shut it off.

Dorrie · 07-25-2018, 03:11 PM

Quote:

Originally Posted by Kent Carter

Count me in! Mine does the same thing and the bedroom ac does it more often. Keystone c/s said it was normal.

This past weekend at about 2 in the am, the one in the bedroom came on for a few seconds and went off. It did this about four times before I had enough and shut it off.

That is exactly what I did!!!! It is very annoying, specially in the bedroom.

Bear6201 · 07-25-2018, 05:45 PM

New 3731FL both the front and the bedroom cycle the fan in the same way as described. I'm in the no idea why Club

wade · 08-03-2018, 08:54 PM

Just bought a montana high country 310RE. It has 2 AC units, the one in the living room/kitchen area is the 15000 BTU is the whisper quite one and the bedroom one has the dump air and they are both all ducted together. the issue is when spending the day traveling in hot weather we reach the campground and the ac is not capable of cooling the camper down. your only hope is that the outside temp drops considerable. YES its been checked out with the dealer and its all good, theirs only 2 degrees difference between the bedroom ac and the living room. the issue is the whisper quite ac doesn't push out enough air from the four ceiling vents , it needs the dump air option on it like the bedroom ac or maybe a internal pusher fan inside the duct work. I've never had a problem like this with any of my other campers I've had because they had the dump air and only one ac to boot. Another problem is that a lot of the campgrounds up here in New England still only have a 30amp hookup so I can use only one ac. not good and not impressed and! and that's just one of the many issues this camper had. The dealer has 68 man hours invested in fixing all the factory screw ups on this camper that was bought new this spring

**DQDick** · 08-03-2018, 09:06 PM

To get better air flow on my whisper quiets I inserted 2 9" pieces of 1 1/2" PVC pipe in each return air vent to open the duct (if yours has the new plastic ductwork you probably don't need to do this, if it's cardboard you do) Then I took each supply duct out, cleaned up the tape and cut the part of the vent that protrudes into the duct down so it didn't block the duct anymore and then I cut every other fin off the vent to open it up even more.

RoadRunnerTR21 · 07-22-2018, 04:53 AM

Our A/C cycling happens more during the high heat in the afternoon and evening. One thing we did notice was that in the morning the rig was like a ice box. The AC would not stop running. DW determined that the problem was that the pantry, which shares a common wall with the thermostat, was very warm inside. When she opened the pantry door to let the warm air escape the AC stopped turning on.

Kyle and Lisa · 07-22-2018, 09:30 AM

The digital dometic thermostats are very sensitive, not as pretty but we pulled the thermostat covers off and leave them off and have a lot less issues - temp., settings, and cycling.

Baldicon · 07-22-2018, 10:56 AM

Another problem (but doesn't explain the fan cycling) is that the thermostat should be mounted as close to the return air registers as possible so it can sense the mixture of air returning from conditioned space. In houses they are usually mounted directly above the return grill if possible. The thermostat in our unit is on the opposite side of the LR from where the return registers are located, but there isn't a good place to locate it close to the return. You don't want to mount it on an exterior wall either. With our LR thermostat set to 79/80, a thermometer on the island reads 74/75. The bedroom operates a lot closer to the set temperature.

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