Rear ac not cooling but front's good?

expansion valve most like. whats the ac pressure gauges say when you hook them up.

 

Not necessqrily, ac refrigerant will follow the path of least resistance, so if your rear is blocked or closed more than the front, front will work better

BUT i THINK that the parksmart system has the sleeper cooling exclusively and the front ac is done only with a crompressor from the engine, 2 completely seperate systems. The way to verify this would be tracing ac lines in the front to see if they go to the back at all.

And rereading, you yourself say the parksmart system is low on refrigerant, so theres your answer. 2 seperate systems, so front is unaffected by rear refrigerant low and vice versa

 

Park smart is what cools the bunk ,for heat it can use park smart or truck engine . When my park smart got low on Freon it kept kicking engine fan due to codes.

 

they dont make freon anymore. the US banned it last year.

 

Semantic point, "freon" generically means refrigerant to anyone only cursorily familiar with cooling systems.

Freon is r22, im not aware of any vehicle uses of r22 as its refrigerant, r134a is the standard as far back as 95ish

 

The people that know enough to help dont care about loose terminology, unless youre the guy that put a few cans of r-12 in your 2015 freightliners system and cant figure out why its not working right... THEN we care about exact terminology