Columbus 320 RS Main AC Freeze Up

[drknight]

My main AC will freeze up after a day or two use especially at night. If I use fan on Auto it still freezes up with AC on. Reads inside temp at 32 degrees but it would be like 75 to 80 inside. After it thaws it will start working again. It is usually when in upper 80’s and 90’s outside when it does this. Not low on Freon because when it thaws it will start working and blowing cold air again. Anyone have this issue and had it serviced? What was the resolution? Replace AC or is there a fix? Thanks for any help and or advice. The unit is a 15k 2-zone unit. I have a 13.5k unit in the bedroom that works fine and keeps bedroom comfortable.

[Bama Rambler]

What brand are the A/C's? Dometic, Coleman, etc.?
Is your RV brand new?

It could be a few things.
1) The freeze coil isn't against the evaporator fins correctly.
2) The partition between the supply and return is leaking or missing. (It's behind the grill.)
3) The ducting could be crushed or blocked enough to restrict air flow and that will cause it to freeze up.

Also try running the fan on Hi instead of Auto. It moves more air that way and can keep it from freezing up as quickly.

[nayther]

ducted system or not? if ducted I's suspect the supply to return plenums are not propberly sealed and air is short cycling. Also not clear on "reads inside temp at 32" is it set for celsius? If the setpoint is around 72 and the thermostat is reading 32 there should be no cooling on at all.

[rockfordroo]

Some models have a "freeze sensor" on the evaporator. The sensor shuts off the compressor but leaves the fan running until it senses no freezing. There have been reports here on the forum of the sensor coming loose.

[drknight]

It is a Demotic and is a ducted system. The thermostat is set on Fahrenheit so that is not an issue. When it shuts off it is reading an inside room temperature of 32. It freezes up no matter whether it is on Auto, Lo, Med, or Hi fan speeds.

I have not pulled the cover off the unit to see if the sensor has come loose or any issues with ducting. Is the panel that separates the supply and return something that you can inspect with the cover removed? At 3am this morning after shutting the unit off at 10PM because it was froze up again, it appeared to have thawed and ran the rest of the night and until noon today without any issues. Has done this multiple trips since last year. Since it starts working again did not think taking it in to be fixed would be possible since it is working. It is back in storage and I will go there in the next few days and remove the cover and see if I can see anything that looks odd.

Thanks to all for your suggestions and I will keep working on this. When it is working it cools the RV as expected, just goes on the blink after it has been cooling for a while.

[drknight]

Unit is a 2016 bought new in August 2015 from Northgate RV in Alcoa, TN.

[bigmurph]

Could be a dirty air filter. My coleman has done it when the filter is dirty.

[mgas]

I don't have any solutions, but I can sympathize with you. My creek does the exact same thing but backwards, the front unit craps out and the rear works fine. I have taken it to two different dealers and they both told me everything is fine. It has become an exercise in frustration.
I thought it was down to the remote temp sensor or the control board, but since yours is opposite mine, I think the remote temp sensor has nothing to do with it. I may replace the control board this fall and see what happens next spring.
Good luck.

[RPCP]

it absolutely can be low on refrigerant. The warmer weather is when you have longer run times which will allow it to freeze up. It would still cool some even slightly low as most of these units only hold around one pound of refrigerant so only a slight leak hurts performance. When the system gets low enough to not freeze up, it will not be cooling either at that point. as others have pointed out, there could be other reasons for your issues, I just wanted to clarify that it can still cool well in mild conditions and freeze up in the longer run times if it's low on refrigerant. As others mentioned, there could be other causes as well. My Columbus is only two years old and I have already had problems with one of the A/Cs doing the same thing. DW thought someone was throwing rocks on the roof of the camper when the ice started melting and getting slung in the airstream by the fan. I was on a trip and added a valve and refrigerant to get it through the rest of our vacation. I have not done a leak search yet as I know it will be difficult to find such a small leak. Yes, I am a licensed hvac contractor so I violated no laws by doing so and would not recommend this as a homeowner repair. I am planning on replacing the unit over the winter. This also does not answer your question about the 32 degrees.

[drknight]

Thanks for the replies. When it is cooling it seems to be working but the 32 degree F issue happened last season as well and I installed a new thermostat and it read the same thing. I think I will call the dealer and talk with their tech about my issues and see what they say. See if they have any thoughts. It works and cools down when it is not on the fritz but I can never predict when it will happen and therefore give the tech a problem to solve. Short of replacing the unit I don’t know what else I can do if the dealer can’t find the problem.

[tomkatb]

It is a good idea to inspect the unit with the cover off. It could be filthy.

The coils will get covered in crud in some situations.

If the unit does not freely flow they do this.

Duct blockage is also a potential issue.

In temps under 90 my front unit seldom runs. If the second unit runs a lot check ducts.

[DouglasReid]

Originally Posted by bigmurph

Could be a dirty air filter. My coleman has done it when the filter is dirty.

My thoughts exactly, when did you last clean the intake air filter?

[Shroomie]

Originally Posted by drknight

Thanks for the replies. When it is cooling it seems to be working but the 32 degree F issue happened last season as well and I installed a new thermostat and it read the same thing. I think I will call the dealer and talk with their tech about my issues and see what they say. See if they have any thoughts. It works and cools down when it is not on the fritz but I can never predict when it will happen and therefore give the tech a problem to solve. Short of replacing the unit I don’t know what else I can do if the dealer can’t find the problem.

If the filter is clean it's probably the evaporator coils need cleaning. You said you bought in Tennessee. I also live in Tennessee. Where abouts are you? If not far I could come take a look at the supply/return plenum and coils. It's hot and humid here and I'm still using the original 05 dometic a.c. 13.5k, runs like a champ. Make sure your air filter isnt getting sucked in at the corners or being bypassed to allow your coils to get gunked up

[Shroomie]

14 years old original dometic run daily for the past 2 summers.