A/C issues, 2001 379

If the system is full of freon, it sounds like possibly the expansion valve is sticking.

 

are you in a high humidity area?

are you running a max a/c?

 

If you have a 379 with a bunk it holds 5.5lbs.Mine did the same thing.Your front ac(cab) uses an orfice tube instaed of an expansion valve it is located it the high presure line right were it goes through the firewall,u have to evac the system to replace this.the bunk ac uses an expansion valve but won't cause the front cab to stop working.Your problem is the orfice tube or the thermastat switch.The switch can be replaced without evacing the system.It is located in the evaporator it's a switch with two wires on it with a long wire the pushes through the centre of the evaporator and senses the temp of the core and tells the compressor when to cycle on or off depending on the temp.Its not telling the compressor to shut off so its freezing up,the pressure gets high in the high pressure line than the comp shuts off.a GOOD WAY TO TELL IS WHEN YOUR SYMPTONS START HAPPENING WHEN YOUR PARKED TURN ON THE HEAT FULL AND GO OUTSIDE AND SEE IF YOUR AC DRIP TUBE IS PISSING PUT LIKE A GARDEN HOSE,THEN U KNOW ITS FREEZING UP FOR SURE.

 

do you have a dryer unit that has a little siight glass/window on the top of it? Lots of bubbles are a sign of a low charge, which could give you this kind of results too.

 

that year will use an acumulator dryer on the low side going back to condensor,no sight window. Those styles are used on receiver dryer high side.

 

Hey im new here im having same issue replace my orifice tube and it blow cooler than it used to be but it still freezing. I have same truck as u my question is how do i get to the thermostat switch or how does it look like so i have kind an idea what im looking for once i work on it again. Thanks.