A/C not cooling

Is the truck you are refering to the 379 in your avatar?

If it is those trucks have a seperate heater core and expansion block for the bunk and if there is a blockage with either of those the rear may not work as well. as long as the front is working than your compressor is good as well as your freon level.

 

Could be the evaporator freezing up and the freeze switch killing the a/c. When it started to blow warm, did you notice if the compressor was still running or not?

 

Did I read you add 2 gallons of antifreeze at a time? You have a leak there. My truck would run for months and barely used any.

Sometime running the fan on high will over power the Evap and you will get warm air. Not enough freon will cause the evap to ice up, that will cause warm air. Always be sure to add freon that has compressor oil in it. As the freon leaks from the system, oil leaks too. If you keep adding freon and no oil, the compressor will burn out, you dont want that. It could contaminate the system and it will be costly to repair. Wet areas around pipe conections could be a sign that it has a bad seal. Good luck.

 

Here's the problem with the bunk air temp. Peterbilts of that era don't shut the hot water off to the sleeper,or cab units. They have an actuator that simply moves a door from the a/c core to the heater core!! Those actuators are notorious for going out!!

 

2 gallons of oil and 2 gallons of water as often as you stated is certainly something out of the ordinary. I can go a whole year without adding coolant. I run about 20k miles between oil changes and maybe maybe maybe might have to add 1 qt to half a gallon. This too depends on if I really had to work the engine more than usual. Look into those 2 issues for sure. As for the A/c. I ran into the same issue and have read on other threads that it is more than likely going to be the expansion valve in the bunk. This past week I replaced the comp, the dryer, the orifice tube, blew out all the lines, the evaps(both), as well as the condensor. Both actuators and blend doors work. I put an hour vacuum and recharged it and it still blew "cool". I researched afterwards like a dummy and read about the expansion valve. Atleast I narrowed it down and have new system aaaannnnd new tools(toys).

 

The a/c will normally cool 20 to 25 degrees below the outside temps.
When it's 104f like today, and you have the hot sun bouncing off the dash into your face, it's still going to feel hot.
Drive safe
Mary

 

Not saying that this is not scientifically true. Yet, @ 104 outside temp, my thermometer stuck in the vent read 80, and my friend's 379, parked next to me read 66. Plus, if momma says it ain't working, then it ain't working.