Ice in the A/C

[lawnspecialties]

Any idea what causes this? We have a Dometic on our Work & Play. It has to work pretty hard to keep it cool at our races. The first time it happened, the ice got so bad it stopped the A/C and caused the 30A power cord to overheat and slightly melt at the connection to the camper. That was late last year and we had no issues again but rarely used the A/C. Then recently, it iced up again. It didn't get so bad to stop the motor but when we turned off the A/C and then restarted it later, the ice had melted enough to get blown out the vent onto the floor. Some pieces were big enough you could use in a drink.

I pulled the cover on the unit and everything looks great. No wasp nests or mouse houses or anything. In fact, everything looks almost new. It has that styrofoam shell over the majority of the parts and everything is really clean and the cooling radiators are in great shape.

The camper is still under warranty but the dealer is 100 miles away and I wouldn't have time until late June at least.

[Dave_H_M]

appreciate the update.

[TUCQUALA]

rhagfo may have the real answer. Look here for more info:

http://www.irv2.com/forums/f282/insulation-barrier-in-ac-unit-249706.html

Ours wasn't totally loose or out of place, but sealing all sides of it did increase the a/c output.

[navegator]

We were in Desert Hot Springs, North of Palm Springs with a night temp of 106 and some humidity, I set the Dometic fan to low and max cool, at about 3 in the morning it froze up, used wife's hair drier to thaw, reset braker turned a/c on high fan speed max cold, latter that week we hit 120 day time and about 108 to 110 at night never froze again, park manager said to run it full bore he experienced the same problem couple of years prior.

navegator

[CavemanCharlie]

lawnspecialties wrote:
Don't you hate it when someone starts a thread and never resolves it? Well not here my friends. 🙂

Our last race of the first half of the season was June 14. But instead of ice or cold air, the AC was blowing only a mediocre cool breeze. We already had an appointment at the dealership after that race so I wasn't too mad. They said they were just going to replace our unit. Well, sure enough, when they tested it today, it was extremely low on freon.

Somewhere, somehow, this sealed unit had a minor leak and that was the source of our problems. I ran the new unit today for almost an hour when we got home. Nice and cool, no ice, or anything.

Thanks to everyone for your suggestions. But I wanted to follow up in case anyone else goes through a similar problem. 🙂

Thank you for your follow up !

[TXiceman]

rockhillmanor wrote:

wa8yxm wrote:
A/Cs ice up for several reasons....Some say even fan on low but I tend to discount that.

thern snowbirds who turn the a/c on and on high fan, all the time.

He swears by running the fan on "low". Laymen's terms so it has a chance to melt off. On high it promotes freeze especially in the hot hot humid south.

Obviously, the tech does not have any real knowledge of the an A/C system and how they operate on the thermodynamic side.

A properly cleaned and running system will not freeze on high speed.

Time to look for another RV tech.

Ken

[lawnspecialties]

Don't you hate it when someone starts a thread and never resolves it? Well not here my friends. 🙂

Our last race of the first half of the season was June 14. But instead of ice or cold air, the AC was blowing only a mediocre cool breeze. We already had an appointment at the dealership after that race so I wasn't too mad. They said they were just going to replace our unit. Well, sure enough, when they tested it today, it was extremely low on freon.

Somewhere, somehow, this sealed unit had a minor leak and that was the source of our problems. I ran the new unit today for almost an hour when we got home. Nice and cool, no ice, or anything.

Thanks to everyone for your suggestions. But I wanted to follow up in case anyone else goes through a similar problem. 🙂

[Chris_Bryant]

The freeze sensor is there just because of bad installations- a clean, well installed air conditioner will rarely actually cycle on the freeze sensor (only when the outdoor temp is in the 70'a or below)- it's there because when they first started ducting these units, OEMs did a horrible job of duct design and install (as compared to the bad job they do today :P).
While the freeze sensor will keep the coils from freezing, the reason the unit is cycling on the freeze control should be addressed- lack of air flow or recirculating air.

[time2roll]

1L243 wrote:
Hmmmm that must be why mine blows hot air when it seems overworked?

Overworked might also be a poorly positioned sensor that waits too long to cycle the compressor.
Get in there and check it.

[1L243]

Hmmmm that must be why mine blows hot air when it seems overworked?

[Chris_Bryant]

1L243 wrote:
What does the sensor do when it sences Ice?

It shuts off the compressor when the coil temperature gets below freezing, turns it back on when it warms quite a bit.

[1L243]

What does the sensor do when it sences Ice?

[time2roll]

If you have a wall thermostat it will have a freeze sensor on the inside on the evaporator. These frequently get poorly positioned and fail to sense the ice.

If it is an integral thermostat you will do best to set the thermostat where the compressor will cycle. Fan set to high speed and continuous on.

[CavemanCharlie]

Also make sure it can drain the water easily. If there is a puddle of water in the bottom that never drains it can make it freeze up quicker. Maybe the drain is plugged?

If nothing else works you may have to turn it to the Fan setting for a few minutes each hour to allow it to unthaw.

[1L243]

I can't remember having a icing problem but on real hot days when the AC felt over worked it would stop blowing cold air. I was running it on High. Running lower seemed to work on that particular situation.

I found that one AC was just not enough So I added a second AC to the garage. Lucky for me my unit came as 50amp and prewired for the second AC... That said before I added the second roof AC I used a portable AC in the garage. I vented the 4" ac duct through the lower flip air vent in the garage. I used a plastic rubber maid box that just fit over the vent, mounted it to the vent then cut it out for the 4" exhaust. You would need to plug this AC in seperate to the power pedestal and not to the RV.. May work for you if you have 30amp setup and can't add a second roof AC...