Regulating cab temperature

You need to get hooked up to ESA. This HVAC is computer controlled. Most likely bad temp actuator or broken temp control door.

 

I know nothing about the new trucks. Do they have coolant shut off valves, and if not would it be a possible solution?

 

Nothing Paccar has water shutoffs on the engine since the days of CAT engines maybe 2006 and older. I have seen them installed on some gliders and it wont hurt a thing. Unfortunately it wont fix this one.

Petes 320 and 520 cab over does still use a water valve for heat control but it is still electrically controlled with an actuator.

 

T660 is a B cab so it would have an actuator controlled water valve for cab temperature control. Pretty easy to feel with your hands on coolant hoses if valve is working or use temp gun.

 

Dang, you just exposed my inexperience with KW product. Lol Thanks for correcting.

 

Just because the computer says an actuator is working, that doesn't mean that it is. If yours is like mine (09 T660) the actuator is under the hood, passenger side, directly below the HVAC unit. You should be able to follow a coolant line to it.

Using a flashlight, you should be able to see the stem of the actuator. You might need to twist the assembly a little. With someone inside turning the knob, look for movement. If the stem just clicks, it's bad. If it turns, it's okay. I'm replacing mine as soon as I find a KW dealer.

This is what the actuator looks like:

The round bit by my thumb is where it hooks to the valve. You will see the valve turn, not this plastic bit.

 

@spsauerland I wish I had these pictures before I went looking for mine