AC evaporator keeps freezing up.

It's a tiny tube that looks like a wire. It runs along the evaporator and the end of it sticks into the core of the evap.

 

We have a different problem. ac is good at freeway speeds but as soon as we idle it starts to blow warm up front. As long as the front is blowing hard (even though warm) the back will still blow relatively cool. Not as cold as when driving but still cool. If I turn the fan down up front the back ac gets warmer. We suspected low freon so had system evacuated and recharged. Freon was low at 1.5 pounds but the 3.7 pounds they put in did not fix the problem.
This is an 2009 780 with Cummins ISX engine
I am not a mechanic but I suspect the evaporator. Thoughts? Suggestions?

 

Can you turn the engine fan on manually? Maybe the fan is not cooling the A/C when sitting.

 

Do not have an engine fan switch on this truck. Don't think that is it however as that would not explain the difference in the sleeper a/c.

 

FOR NOCOCRAIG !

unscrew the bolts holding the condeser, move it with care as much as you need to work with an air blower gun on this condenser. give a good clean. I suppose you will a lot of things coming out, paper, insects, dry mud, pieces of hamburgers, frenck fries,lipstiks or whatever the 4 wheelers are throwing trough the windows.

 

Now, I've seen what a woderfull english I've had on the previous posting. Sorry! I was very tired at the time. Anyway, I'm hopping that solved your problem. Please, let us know if it did.

 

Install shut off valves on the coolant lines going into sleeper unit and front unit,that is the problem coolant is circulating while it should have. When you don't need ac in cold weather just open valves.

 

this is not a problem with sealing the housing, it is almost guaranteed a blocked drain tube. Do you see water dripping on the ground from near the front of the passenger area when stopped? If not then the water that is condensing on the coils is building up and filling the compartment. It is sealed just fine, that is why it fills up. Find the hose and use a coat hanger or something to run up through it and clear it our. It usually doesn't take much crud to plug one of these.

 

Clean your drip tube it's probably clogged

 

Had that happen before.