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Open Roads Forum  >  Tech Issues

 > Air Conditioner Freezing up and almost no air flow through the vents.

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Lawman5383

Cypress, TX

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Posted: 05/17/04 02:20pm Link  |  Print  |  Notify Moderator

I have a 2004 Crossroads Cruiser 28BH equipped with the Dometic 15K BTU Quick Cool air conditioner. On the last couple of trips we have had a problem when the thermostat is set below 74 degrees or so. Something seems to be freezing up and the air flow is almost non-existent through the vents. This primarily happens on not hot, but warm days. I returned it to the dealer to get it checked out and once they called me back they said they could not duplicate the problem. Looking for anyone else who may have had this problem or might have a suggestion.

Thanks

Allen


2007 Cedar Creek Silverback 33LBHTS 5th Wheel
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Jiver51

Meridian, Mississippi, USA

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Posted: 05/17/04 02:29pm Link  |  Print  |  Notify Moderator

If unit is low on freon, the coils will freeze and this will block airflow. Have AC unit serviced.


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SkipnPatty

Mt. Airy, MD, USA

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Posted: 05/17/04 02:29pm Link  |  Print  |  Notify Moderator

UhOh! Just bought a new Cruiser ourselves. I had the exact issue with my Coachmen TT. Got almost unbearable on one hot weekend. Same thing at the dealer. Only suggestion I ever got was to not turn the air conditioner below 76 degrees. If you need it colder that makes it difficult. We kept it at about that level and were okay, just frustrated that these units are designed as such. Did a lot of searching and never got anywhere with it.


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saladohr

Salado, Tx

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Posted: 05/17/04 06:58pm Link  |  Print  |  Notify Moderator

Had the same thing happen to a rental TT while at Lake Livingston, east Texas humidity. Turned the unit to fan for a while to melt the ice and made sure the entry door remained closed as much as possible and had no more trouble.


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Jake & Alma

St. Catharines Ontario

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Posted: 05/17/04 03:08pm Link  |  Print  |  Notify Moderator

Allen,
The a/c units will ice up under several conditions, the most common is low air flow, make sure the filter is clean, all vents are open and the flow directed away from the unit, also select the high speed fan operation. You also mention that it tends to ice on warm days more so then on hot days and that is typical of a/c units, when the outside temperature is lower the unit has slightly more capacity which causes the indoor coil temperature to drop below freezing and the condensate freezes on the coil. It seems both the rv and a/c manufactors are to blame. The a/c makers have reduced the airflow somewhat to make a quieter unit and the rv should have larger ducts to allow for this reduced fan speed. There are automatic deicing controls available that can be added to any unit. Jake

panchovilla

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Posted: 05/17/04 03:04pm Link  |  Print  |  Notify Moderator

As Jiver51 said - it will freeze up if it is low on refrigerant - However, it will also freeze up in high humidity conditions. The same cure applies, run it for awhile with the fan/blower only until you feel warm air coming out of it and then set it to "Cool".


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LARoberts

San Jacinto, California USA

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Posted: 05/19/04 11:41pm Link  |  Print  |  Notify Moderator

We also had the same problem on our 1993 Thor / Fourwinds / Majestic, class "C". The air conditioner is a Coleman.

It started after leaving San Diego a few years ago in July 2002. In Kingman, Az, we stopped at a RV repair shop. He put a temperature gage on it and said because of the high humidity, the reduced cool air coming out of the ducts was normal. Looking at the air conditioner on top of the RV, you could see ice on the lines.

We could not believe this was normal, 100+ degrees outside plus humidity and nothing worth while coming out of the air conditioner.

When we got to Colorado Springs, Co, I called the Coleman company. I explained the problem to them and after a few questions and answers they asked what the thermostat was set at.

After I mentioned we had it down to around 50 degrees, they said the air conditioner, at best, was able keep the coach about 30 degrees cooler than the outside temperature.

They said to keep the thermostat at about 75 degrees and we should not have any problems.

After this, I thought it was about time to read the instruction manual / booklet on the air conditioner. In the manual it basically said there was a temperature switch that shuts down the compressor if it freezes to prevent damage to the unit. After it cooled off and the ice melted, if it did freeze up, the compressor would start up again. Since we had the thermostat set so low, the compressor never turned back on again after it froze up.

After the thermostat was sent at 75 degrees (it was still 95+ degrees outside) our air conditioner never froze up and it worked very well.

This is what our problem was, operator error.

Larry & June

Chris Bryant

DeLand, Florida, USA

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Posted: 06/21/04 04:35pm Link  |  Print  |  Notify Moderator

If this is a ducted installation, there should be a "freeze control", which will shut the compressor off if the coils go below 32° .
If you remove the filter, it should be clipped to the coils in a cutout on the curb side (IIRC).
Coleman units use a thin probe which goes into the coils.


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TimHayden

Seekonk, Ma, USA

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Posted: 05/20/04 04:44am Link  |  Print  |  Notify Moderator

Any freon air conditioner will have the evaporator coils (cold, inside) cold enough to cause the condensate to freeze. If the interior air is very high in humidity, this can lead to excessive ice which will block the air flow. One solution is to set the thermostat to allow the compressor to cycle. When the compressor goes off, the evaporator coil will warm up and the air flow - let's say it is 80 inside, will warm up the coil and melt the ice. The condensate will drip off the coil and run outside. Then when the compressor starts up again, the whole cycle will repeat - but you have given some time for the ice to melt, instead of it just building up thicker and thicker. The thicker the ice is, the longer it will take to melt. The more often the compressor is allowed to cycle off, the thinner the ice layer will be and the quicker it will melt.

My suggestion is to set your thermostat 5 degrees below interior temperature and allow it to settle out, with the compressor cycling. Once it has cycled a couple of times, turn the temp down another 3 - 5 degrees and repeat the cycle. This gives time for the ice to melt when the compressor is off and the amount of ice / condensation will be reduced slowly as the humidity inside goes down. Alow, take steps to reduce the amount of humidity inside - keep door closed as much as possible, don't cook inside, don't take a shower, etc.

Also, unless the A/C is a two stage unit, it gives maximum cooling whenever the compressor is running (with fan on high speed) regardless of whether the thermostat is set just below the interior temp or it is 20 degrees lower than interior temp.

bubba-1

Sitka, Alaska

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Posted: 06/21/04 04:27pm Link  |  Print  |  Notify Moderator

Many times when the temp or humidity are high and when the AC is not running on high speed, the ice will form on the condenser. If it freezes up, just turn the unit off and let the ice melt then restart. Works for me!

Mick
2001 23.5 Lazy Daze FL
Sitka Alaska


MICK

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