A/C Question

[NATRDYSANDCO]

Hey folks,

I've tried the search function.

I have a 2010 Sunset Trail 24RB with what I believe to be a Dometic A/C system. The last few times weve been camping with the A/C on, over time the A/C would not cool the camper anymore. It never fails, A/C works fine when you start it up, runs fine for about 4 hours or so, then starts to blow warm air. This last time we went camping I was able to get up on the roof and pull the shroud. Frozen piping from the compressor to the condensor and frozen fins and cooling tubes on the condensor. Compressor was warm. We were able to thaw the ice and the ac would work again just fine until it iced over again. The other problem that I had just recently realized was that the compressor was kicking on and running non stop as soon as the coach was hooked into eletric regardless of the thermostat setting and could only be cut off by the cutting the breaker.

I think I may have a thermostat problem, but am not sure and before spending a 500-600 bucks on a new system that is backordered everywhere, wanted to see if there was another answer.

Thanks.

[Stan]

Normally when the fins and system freezes up it means you are low on coolant (R-22?). Not positive what they use these days.

[travelin texans]

Originally Posted by NATRDYSANDCO

Hey folks,

I've tried the search function.

I have a 2010 Sunset Trail 24RB with what I believe to be a Dometic A/C system. The last few times weve been camping with the A/C on, over time the A/C would not cool the camper anymore. It never fails, A/C works fine when you start it up, runs fine for about 4 hours or so, then starts to blow warm air. This last time we went camping I was able to get up on the roof and pull the shroud. Frozen piping from the compressor to the condensor and frozen fins and cooling tubes on the condensor. Compressor was warm. We were able to thaw the ice and the ac would work again just fine until it iced over again. The other problem that I had just recently realized was that the compressor was kicking on and running non stop as soon as the coach was hooked into eletric regardless of the thermostat setting and could only be cut off by the cutting the breaker.

I think I may have a thermostat problem, but am not sure and before spending a 500-600 bucks on a new system that is backordered everywhere, wanted to see if there was another answer.

Thanks.

On the thermostat try setting the fan to "hi" rather than "auto", the fan will run constantly which usually keeps it from icing up.
As to low freon, most RV air conditioners do not have ports to add freon & most HVAC techs won't or aren't allowed on a RV roof due to their insurances.
Typically if an RV ac quits it's replaced rather than repaired.

[dagst1]

Restricted air flow will cause it to ice up also. Be sure to check and clean the filter. Also on the roof make sure the fins are clean. Take a hose and flush them out. Should help.

[Russb]

This link may be helpful.
https://lifeonroute.com/reasons-your...ed%20regularly.

[Busterman1958]

As dagst1 said always check air flow, filters, coil, in and out good luck.

[TerryH]

Pull return ceiling grill. Should be FREEZESTAT SENSOR MOUNTED TO COIL. If not properly mounted, cannot sense ICE. FREEZESTAT shuts compressor off to defrost; Set fan AUTO/ON = ON; set HI/LO. To HIGH (will freeze lessons defrost faster. This controls compressor thru circuit board relay, so thermostat or circuit board also possible causes. Design is to run below freezing to give air as cold as possible. Should defrost fast w/ compressor off and fan on high. And then compressor comes back on. DIRTY COIL OR FILTER can cause excess icingvdue to low air flow, as can failing/ dragging/ seizing fan motor. Hope this helps. Freezstat denser can also be off and need replacing. You can measure value against a table of values by temperature.

[fnPauly]

I did Air Conditioning repair for many years in the south, including RV AC units, but haven't in 30 years. Low freon can/will cause the coil to freeze. Unless the unit has a leak, the freon would not normally be low and it doesn't wear out. If there is a leak, usually you will see an oil stain on the copper (or aluminum, YUK) line or in the coil itself. Much of this is hidden and not easy to access.
The number one reason for the AC to freeze up is the evaporator coil (the coil that the inside air blows through, not the outside one) is clogged with dirt/dust/lint/etc. This causes the air flow to be reduced enough that the coil will ice up.
The filter that comes with most RV AC units is crap and let's way too much dirt get through. But, it works well enough to get the unit out of warranty
I think the evaporator coil needs to be cleaned. The problem, if memory serves me, is that coil is kind of hard to reach. As someone suggested, you can drop the ceiling grill. Then use a flash lite and look up in the dark cavity and see if you can see the coil. If you google "dirty RV evaporator coil" you will have a bunch of links to videos on what it takes to clean one. Be careful, it is almost never as easy as the videos suggest. If you click images across the top, it will show some pictures of where the coil is.

Good Luck!

Paul