2017 Peterbilt 579 Heat not properly working

Did you actually do the hvac actuator test with ESA where it lists off all the actuators and a pass/fail? Checking codes is not good enough,

Are the hoses heading to the heater core hot? Are they hooked up the right way? It does have a coolant bypass valve on it that can fail.

 

Nice diagram well to be honest you are correct I don’t think the pass fail test was done I need to look into that I can borrow the laptop tomorrow from my friend and see if I can do that test yes the valve I’ve replaced 2 times another note for the sleeper is there a separate heatercore or lines or they are ran together from the main heatercore and yes both those hoses are super hot to the touch the in and return

 

Those heater flow restrictors and bypass valves mentioned in the diagram seem awful suspect. Your getting warmer air, when you rev the engine, indicates a water flow problem.

 

good morning forum i have an update im on the ESA software from a buddy and i think i might have found the issue i removed the tempature actuator and unpluged it and plugged it back in it didnt move so i i rebooted the ESA program and now im getting 2 codes could this mean the head unit is bad? seems like the tempature actuator is not getting signal its plugged in and it dosnt turn its also new i changed it 2 times in the last month here are the codes and details.

Heating, Ventilation, and Air
63902 Active
HVAC J1939 communication fault 0 127 Conditioning Detailed Description
This DTC will be reported when the HVAC head unit detects an open circuit or short in the J1939 datalink. Check performance of CAN participant, connection between the control head and the body controller, for a short circuit, or the HVAC control head unit.

Heating, Ventilation, and Air
398602 Active
HVAC temperature actuator fault 0 127 Conditioning Detailed Description
This DTC will be reported when the HVAC temperature actuator is in the wrong position or is jammed. Check temperature actuator, door, and connection

 

Ignore the 1939 fault unless it keeps occurring.
The second code is probably the issue.
Go to either monitor or simulate, cant remember which one. Then to HVAC, then HVAC self test and see what the result is.

 

i will be doing that tomorrow it seems today it worked had heat but i did notice it doesn't get hot even if i idle for more than a hour it gets to 150 and gets a little warm not hot unless i rev the rpms to 1400 for about 2-3 minutes it starts getting hotter haven't tested it on the road since its snowing here and don't want to go far out tomorrow i will try look for the test today i was playing with it and could not seem to find that pass fail test

 

I give up same issue I’ve done everything except change the controls because there is none available could that really be the issue ? Like how can that control the heat to pass thru

 

ok a little update i been messing with everything i one hose from the heater is hot the other is cold i think the cold one is the input when i rev up the engine to 1400 from idle gets a little hot what can cause the input hose not to get hot?

 

i did the test all pass now one of the hoses is not hot that go to the heatercore its the hose on the driver side i believeits the input? what would cause this? the valve is new what else can cause this the input where does it come from ?

 

the outlet hose coming from the 4way valve off the heatercore is cold means clogged heatercore? heatercore 1 month old? any ideas?