AC doesn't work while idling Peterbilt 579

it wouldn't "naturally need" a charge. check for oily residue around ad many fittings that you can see.

check for chafing hoses that might be touching each other, or against another part under the hood.

i would try to take off the housing in the sleeper and check for dust/dirt/grime, clogging the evap back there.

you can also check the evap box, under (usually) the passenger side just under the dash, for same clog.

you can also check for the water drip hose for drainage. (usually) around the passenger side, under the hood, it will look like a short piece of rubber hose.

your a/c system ,may or may not have a sight glass, that you might be able to see freon passing thru.

 

When you say sorta works,do you mean blows weak out the vent ,till the blower motor spins up.If so ,Id be looking at blower motor,vent control motor,or a relay.Id start with blower motor.

 

On a truck that new, it's most likely an actuator for one of the airdoors. Try shutting off the water to the heater core and see if that helps. These newer systems always have hot water flowing thru the core and use airflow doors to manage the output temp, most likely the door isn't fully shutting off the air from the hot side.

 

Not sure. I know Detroit moved them up on the right rear where they're easy to find. Just trace the heater lines. Usually one for the cab and one for the sleeper.