Dometic A/C help please.

[Tbonz]

First day of vacation at Ft Richardson state park. Central Texas.HOT!!!!!!..FRont ac will cool for a while then compressor cuts off and it stops cooling. Then in a coople minutes the cpmpressor comes back on and it cools..Keeps playing this game..So I am wondering if I have a thermostat problem..Any ideas are welcome. Thanks. Terry.

[valleyduo]

How long is it running before it cuts out? is there a vent that blows directly on your thermostat? Compressors will cycle off when the thermostat reaches it's set point so anything that may cause the thermostat to get a cold blast could give you a false reading. Also make sure the thermostat is set where you think it is. Ours likes to change temps on us. I believe the kids do it, but no one ever fesses up to that.

[Tbonz]

Originally Posted by valleyduo

How long is it running before it cuts out? is there a vent that blows directly on your thermostat? Compressors will cycle off when the thermostat reaches it's set point so anything that may cause the thermostat to get a cold blast could give you a false reading. Also make sure the thermostat is set where you think it is. Ours likes to change temps on us. I believe the kids do it, but no one ever fesses up to that.

None of those..I re crimped the thermo wires inside AC cover..Seems to be doing better now..Hopefully..Too dern hot for an AC to play silly games!!!Thanks for replying.

[Tbonz]

Earlier it was running about 5 minutes..been going for 30 now..Thanks

[Tbonz]

Been going for an hour..as a matter of fact my feet are getting cold.!!!

[Flybob]

If you try to cool a very hot humid RV too fast, many times the coils will freeze up and it will shut off to thaw. If you have a ducted system, open the dump valve fully so you get max air flow and as the RV cools and the humidity decreases slowly close the dump valve to divert the air through the ducts.

[Tbonz]

Originally Posted by Flybob

If you try to cool a very hot humid RV too fast, many times the coils will freeze up and it will shut off to thaw. If you have a ducted system, open the dump valve fully so you get max air flow and as the RV cools and the humidity decreases slowly close the dump valve to divert the air through the ducts.

Thanks..seems to be fine now. I didnt see any ice on coils. And when i shut it down for a reset there wasnt a flood pff the roof..

[jking46]

Dometic had a bad run of thermostats. Actually not the whole unit but just the cover. Causes the numbers to change and not maintain a function or temp.
Call Dometic and they will send you a new faceplate. Or if still under warranty, call your dealer.

[Tbonz]

Thanks for all..seems to be working well now.

[eddy53]

Sorry to say it's a dometic air conditioner the standard of production is so low now as its made in China that your not the only one with problems, get on to them and at least log the fault the more they get the better and then they might think of the customer instead of the share holders.

[mwdilday]

Check your filter if you haven't already.

[Mr. Dan]

Hello, all........... the OP has reported that his unit seems to be working well now.

Originally Posted by Tbonz

Thanks for all..seems to be working well now.

[Tbonz]

Good news..AC has been going strong since Friday afternoon..Hopefully it is fixed.

[Herk7769]

Hot and humid is not the time to set the AC to 65 and let 'er rip.

A brief explanation of AC techniques can be helpful in understanding why.

Air Conditioners need to remove the humidity from the air before it can start really cooling efficiently. To do that, the air conditioner must cycle on and off to let the frost/ice melt into the drip pan and run off the roof.

There is a sensor on the cooling coils that prevents the compressor from running when the coils ice up. This is to prevent the compressor from overheating and become damaged.

So how do I use my AC in hot/humid?

I set my thermostat to 10 degrees below the outside air temperature (or 90 if it is over 100 degrees outside). This gives the AC a chance to start dehumidifying the air by cycling on and off to maintain the set temperature.

Believe me when I say that walking into a 10 degree cooler interior feels good (not great, but good).

As the air inside the camper dries out, you can begin to slowly reduce the inside temperature to your desired coolness. Remember that opening the door will let that hot humid air back in so keep an eye on the door.

Low campground voltage can also effect air conditioner efficiency. That can increase the current demand and cause the compressor to overheat and trip the thermal circuit protection in the motor. It wont start again till the motor cools off. Ice buildup from trying to run the AC full blast on a hot camper can also cause overheating. Both of these can reduce the life expectancy of your AC.

Reduce the "Heat Load" on the air conditioner.

Buy a roll (or two) of Reflectix at the Home Store. The material comes in 24 inch wide rolls, so measure your windows. Remember it can be taped together with box tape to there is very little waste and you can make a big panel for a picture window.

https://www.amazon.com/REFLECTIX-BP2...ords=reflectix

Cut it to fit your windows to reflect the solar load by reflecting the sun's rays. Keep the door closed as much as possible and cook outside.

White campers and roofs work best to reflect the incoming heat. Brown and Black campers may need additional air conditioners due to solar heat absorption.

I hope that helps you.


Herk

[eddy53]

Originally Posted by Herk7769

Hot and humid is not the time to set the AC to 65 and let 'er rip.

A brief explanation of AC techniques can be helpful in understanding why.

Air Conditioners need to remove the humidity from the air before it can start really cooling efficiently. To do that, the air conditioner must cycle on and off to let the frost/ice melt into the drip pan and run off the roof.

There is a sensor on the cooling coils that prevents the compressor from running when the coils ice up. This is to prevent the compressor from overheating and become damaged.

So how do I use my AC in hot/humid?

I set my thermostat to 10 degrees below the outside air temperature (or 90 if it is over 100 degrees outside). This gives the AC a chance to start dehumidifying the air by cycling on and off to maintain the set temperature.

Believe me when I say that walking into a 10 degree cooler interior feels good (not great, but good).

As the air inside the camper dries out, you can begin to slowly reduce the inside temperature to your desired coolness. Remember that opening the door will let that hot humid air back in so keep an eye on the door.

Low campground voltage can also effect air conditioner efficiency. That can increase the current demand and cause the compressor to overheat and trip the thermal circuit protection in the motor. It wont start again till the motor cools off. Ice buildup from trying to run the AC full blast on a hot camper can also cause overheating. Both of these can reduce the life expectancy of your AC.

Reduce the "Heat Load" on the air conditioner.

Buy a roll (or two) of Reflectix at the Home Store. The material comes in 24 inch wide rolls, so measure your windows. Remember it can be taped together with box tape to there is very little waste and you can make a big panel for a picture window.

https://www.amazon.com/REFLECTIX-BP2...ords=reflectix

Cut it to fit your windows to reflect the solar load by reflecting the sun's rays. Keep the door closed as much as possible and cook outside.

White campers and roofs work best to reflect the incoming heat. Brown and Black campers may need additional air conditioners due to solar heat absorption.

I hope that helps you.


Herk

Hi sorry but in a desert there is no humidity, and if I have to go through all of what you said, what's the point of having air conditioning, best to North we're it's cold.

[Tbonz]

Thanks Herk. It was 110 when I turned AC on..I set it to 70. It seems to be doing well now..110 outside 79 in here..fan on as long as I don't do any calisthenics it is cool enough!

[Herk7769]

Originally Posted by eddy53

Hi sorry but in a desert there is no humidity, and if I have to go through all of what you said, what's the point of having air conditioning, best to North we're it's cold.

Reducing thermal loading works in both environments.

This is how I prepared mine for a 6 week trip through Texas, New Mexico, Arizona, and Utah in August a few years ago. We were quite comfortable and used the step down cooling method.

http://www.forestriverforums.com/for...-ac-42280.html

Reflectix is awesome stuff.

[larryi]

Herk,
I've read some of your comments on AC issues and you've provided the clearest information so far. In troubleshooting my AC problem, my Dometic 15k cycles on and off quickly, sometimes the fan shuts down and you hear the compressor continue to run and based on EMS system I can see the amp draw builds to 27amp when it normally runs at 15-17amps. My voltage on that leg of the power is running around 111v if not closer to 120v. Is that enough to cause problems with the compressor? 27amps seems way too high for it to be normal and the fifth wheel is only 2 months old and the whine of the compressor doesn't seem correct. What is normal for amperage spikes at startup?

[Herk7769]

Larry,

I am not an HVAC guy, nor do I play one on the Internet.

It is possible, however, that you have a defective Dometic air conditioner. They did have a bad batch not that long ago and there was a not-so-silent recall on the defective units. Apparently there were many that were delivered under serviced and failed early.

Yours may be one of those so my first call would be to Dometic tech support. They would be the expert on your issue.

The initial start up current for your AC is on the information plate on the side of the AC (on the roof). Look for LRA amps. My Coleman 15k was over 50 amps. The LRA drops so rapidly once the compressor begins to rotate that most clamp on ammeters will not sample in time to catch it at the peak. It takes a special tester to catch that and you can buy the kit from Micro-Air on their web site.

So the first caught sample at 27 amps is normal. Shutting down the fan while the compressor still runs is not unless the thermostat is possibly wired wrong.

When the thermistor detects ice, it is supposed to shut down the compressor and not the fan.

In short, a call to Dometic tech support is the way to go.

Let us know how it turns out;
Lou