I have been told by the dealer that it's not possible to install a heater core shutoff vlv on my second gen 2001 truck but I was pretty sure that the first gen trucks came stock with one, can anyone confirm this? I may be thinking of the gas engine though.

 

The temp control lever (little slider above the buttons) is connected to a vacuum modulated valve in the heater line. Basically a shutoff valve. But I don't know if it shuts off completely except possibly when you have max A/C selected or something like that.

Wanna mentioned something about how that combination works at one point last summer as I recall, but I can't remember exactly what he said.

 

I put in a ball valve upstream of the modulated control which never shuts off all of the hot water. Our AC needs warm water to modulate it. Solution: stick a thermostat from a real good ac into the line to the ac clutch. Put the probe into the evap. Now you can modulate ac like normal people. The hot water needs to be shut down completely to keep things at max cool. With my propane refrig. I can get discharge temps of -12 c.... with the heat shut off.

 

The shutoff valve is closed in the "max AC" and "off" positions. Coolant flows through the heater core in all other positions.

 

Thanks for the replies, I thought I wasn't dreaming this. It's exactly like wannadiesel says is what I want to do, (just tee into the recirc door to shut off during Max AC and Off posns). Now what I don't understand is why the dealer says it's not possible yet the first gen trucks came factory that way? Does anyone know if the heater take off points are the same on gen1 and gen2? My gen2 tees into the bottom rad hose at the block and the other heater line into the cyl head at the number 5 cyl.

 

I have a manual ball-valve in the top hose that gets closed the first of June and opened the first of October, no problems and ice-cold A/C.