2017 Peterbilt 579 Heat not properly working

You need to get everything drained. Disconnect all the hoses from the cab-related stuff. Disconnect what coolant hoses you can from the engine and radiator. Remove the coolant filter. Then, take a garden hose and start flushing every coolant passage you can find. Get everything as cleaned out as you can and start over. I’d go so far as to get a new thermostat, as it’s probably plugged up, too. That’ll allow another place to blast water through the engine. Again, those restrictors and valves need pulled out and looked at. You just have to start over.

 

the coolant was changed about 2 months ago

you are totally correct its working fine just now weird its on the road this weekend i will try to get all that done see what happens

 

If you got to pull t all apart
I would put a box of Cascade in the radiator on your way home.

 

the detergent? someone was telling me it could be the aircooling clogged up? both lines are super hot now and im sweating lastnoght the outlin was cold and inlin hot so has to be something in the system that is blocking it sometimes

 

Yes the Cascade dish washing detergent. Don' t use the liquid !!!

 

wont that mess the internals up

 

Sure won't
But will clean out your system

 

I had a car that acted like that. Turned out to be a thermostat.