Dometic AC

[ronconp]

Another question about our new trailer. When it starts to heat up outside(right now it is 91 and full sun) the AC will turn off and on. Seems to be cycling and the speed changes. It is still cooling, but the off and on thing doesn't seem normal. It will do this every few minutes. Any ideas will help me understand.

[TURBS]

Most likely defrosting is my guess.

TURBS

Sabre owners united!

[ronconp]

Thanks f1100turbo
If it is defrosting would this mean it is low on freon?

[TURBS]

Not necessarily.
It could be hot and humid enough that the lower coils are frosting up.
Try a little warmer setting .
20 degrees difference between inside to outside is about max.

TURBS

Sabre owners united!

[ronconp]

It is set on 80 and 91 out side. Where we are sitting the sun will be off the trailer in about an hour and it will stop the cycling.

[Oakman]

Originally Posted by ronconp

Another question about our new trailer. When it starts to heat up outside(right now it is 91 and full sun) the AC will turn off and on. Seems to be cycling and the speed changes. It is still cooling, but the off and on thing doesn't seem normal. It will do this every few minutes. Any ideas will help me understand.

I believe that is explained in the manual for your thermostat. Mine does that also and has been since we bought our trailer in March 2012.

[ronconp]

Thanks Oakman
I'll check out the thermostat manual.

[Platokidd]

I never noticed that with my dometic a/c on my Lacrosse.
Just a question, you dont have a vent or window open slightly? I think that can make it frost up a bit.

Wish I had a 2nd a/c in my unit. One unit works hard to keep up on hot days with no shade.

[mark0224]

If the condenser on the Ac creates a lot of frost it won't work properly this usually happens when there is high humidity. I had this happen on a car once I just shut it off for 10 to 15 minutes so it thawed then turned it back on and it worked fine for the rest of trip.
It's kind of like defrosting your refrigerator when you do it works more efficient.
What you have described sounds like what I had happen but there could be other things.

[BigJohnD]

The on off thing sucks, but is normal. That's just how the new control box / thermostat works. It decides what speed it wants when in auto, depending on the temp. The older ones had a smooth transition between speeds. First time I dealt with the newer ones on our Forester, I thought something was wrong with it, until I went in several other campers with the same set up. If it's too annoying, just put it on high fan and let it go.

[Platokidd]

Originally Posted by BigJohnD

If it's too annoying, just put it on high fan and let it go.

I guess I should point out I dont use the auto setting. So if that make the difference I wouldn't know.

[mark0224]

Auto will turn it on and of as it is needed and that may make a difference allowing it to defrost in between.

[BigJohnD]

On ours now, and the last one, if you turn it on (assuming it's really hot inside), it'll run on high fan until it cools down a little, then it'll swap over to low fan for awhile until it reaches the set temp. Some units though, seem like they get confused figuring out which fan speed they want in auto. We had the control box changed out in the Forester due to some similar problems. In our present unit, the control box is crap as well. You'll hear eratic clicking sometimes like it can't decide what to do. That's on the list of problems while it's in the shop now.

[ronconp]

You are right BigJohnD
I checked the thermostat Manuel and it states the same. At 4 degrees difference it runs one speed and at 5 degrees a faster I'm going to try it on a single speed. I agree a second AC would help.
Thanks everyone for the help.

[gimp425]

I set the fan to run high all the time circulating the air. I know at night I can tell when the compressor cycles off and on but with the fan on high all the time it won't change speeds. Works well