The Dash AC was recharged 2 years ago, it would run a few hours and then slowly lose the cool. I had the unit evacuated and refilled and the guy said the expansion valve was freezing due to moisture. I did not use it very much until a month ago, it would run about 1 hour and slowly lose the cool.

The in fitting is hot and the out side is very cold. I took it to a guy he found a tiny leak at the compressor but I decided only to recharge the system and change the belt because I did not think that fixing the leak would correct the problem and if I opened the system, and then closed the system I would only need to reopen it anyway.

So he changed the belt and added 1 pound of freon. The unit worked really well for 45 min while the engine was at idle. I took off and 1 hour down the road the cool was gone. I checked the hot water hoses into the heater core, they were hot going in and very warm coming out of the blower box. AH-HA he said, a leaking heater valve, so I put a ball valve on the in and out of the heater. Two ball valves should stop that pesky hot water.

Yes it does, the water is not even warm coming out and not hot going in either.

However the unit will now only run for 30 min and then shut off. Before if I stopped for 2 hours the AC would restart so I figured it was ice in the expansion valve. Now I need to stop overnight and it will blow cold for 30 min and then just be a fan.

I am in Mesa now and headed to Lake Havasau with 115 temps, Yes it doesn't work when I really need it. Above the snow line it works fine

I am running the roof air which is ok.

So if I have freon, have good pressure (compressor is ok), have cold out and hot in on the freon lines, the only thing is the expansion valve or the orifice tube freezing. But why?

Now I won't get it fixed this year as I am leaving in a few days back to Thailand. The next go I will fix it but some advice would be helpful before I go to the guy and have him say, you are low on freon, or "the compressor is too far from the front"

I checked camping world, simply because they will honor a repair at any location but will charge more than most.

Comments.

Tom,
My compressor froze up completely, thankfully! That made my decision easier to just use the generator to power roof air when we want AC. I was so sick of the dash air working only when you didn't need it. It also gives me an excuse to run the generator and keep it exercised.

I am back in NH now and have some time to consider your need for wiring diagrams. I live 40 miles from the nearest Kinkos, so you will need to bear with me. Perhaps I can scan them in pieces.

Good luck on your upcoming trip!

My compressor froze (mechanically)also, I have located another replacement compressor but I am going to wait until I am finished with this years race schedule before I tackle this job. I am seriously considering replacing the entire system, complete with hard line, and a much larger dash unit.

Tom, you may have added to much freon, it was surprising to me how little freon mine took considering the length of line there is involved going from the rear to the front. Just a little over 2 lbs.

All the clamps where the rubber line and metal line meet are subject to leaking. There should be a freeze detector (for lack of better words) that should control the expansion valve so that the coils do not frost over, maybe that has been displaced and not doing its job.

Have a safe trip back to Thailand!

One reason that they freeze up is moisture in the system. I would pull the orifice and clean it and replace the dryer. Also, put it on a vacuum pump for several hours to draw out residual moisture and recharge.