Dash Ac

[George Frudakis]

Any ideas

Dash ac run cold for about 20 mins, then shut downs. I have to wait a about an hr then it will run cold and shut down in 20 mins. I put new coal and compressor. Blow out all the lines, install new Freon but still the same thing.

Thanks for any help
George

[Dale Walker]

Sounds like your condenser is freezing up, could be to much Freon. Did you use gauges when you were refilling the system??

[George Frudakis]

Yes the right amount is.

[Jim Edwards]

I believe that there is a thing called an expansion control valve as Wikipedia describes it: A thermal expansion valve (often abbreviated as TEV, TXV, or TX valve) is a component in refrigeration and air conditioning systems that controls the amount of refrigerant released into the evaporator thereby controlling superheat. Thermal expansion valves are often referred to generically as "metering devices"."

Perhaps this is malfunctioning? When Mine failed I had no cooling but possibly they can malfunction in different ways. ( stuck open vs stuck closed or stuck in the middle?)

Just a thought.

[Gerald Farris]

George,
You description sounds like your evaporator core is icing over, therefore it severely restricts or blocks the air flow and stops the cooling process. Assuming that the charge is correct, you evacuated the system, and ice in the refrigerant is not a problem, you have a bad expansion valve.

Gerald

[George Frudakis]

Thank you
Do you know where the expansion value is located in a 2002 Marquis

[Gerald Farris]

George,
The expansion valve on your coach is located at the evaporator core inlet. If your A/C charging ports are under the front cap, the low side port is 2 or 3 inches from the expansion valve on most coaches.

The accessibility will depend on which model coach you have, and how skinny and flexible you are. If you have a real world 40 or 42 ft. coach and you weigh less than 160 lbs., you can change the valve by standing up between the front cap and firewall. But if you have a California 40, or if you weigh over 200 lbs., there is no way to get to it without removing the dash filler pad that the defroster ducts come through and cutting an access port through the dash, and covering the hole when finished. In fact, I weigh 180 lbs., and that is the only way that I would consider changing one.   

Gerald