I just bought a 2002 F-250 7.3. and my heater wasnt working. as i was looking into why it wasnt working I found an in line valve to the heater core. After I opened the valve the heater did start working, i am not leaking anti freeze in the cab, but i was woundering why somebody would do that. any info on this would be great. thanks

 

Sometimes they are installed to completely remove heat from the cab in the summer months. We do this on our older hi-way tractors, as the coolant is always flowing into the cab, and does create heat. Even when the heat is turned off on the HCAV controls.

 

To help make the AC cooler

 

I installed a valve on my 2000, putting a guage in the vent will shor down to 23* goin down the freeway when its 100*.

 

Yup. Pretty common mod. The Crew Cab trucks came factory with a valve that shut the coolant flow at MAX AC.

 

mine cooled AC temps by 7*

 

common on cab farm tractors. i had a motor home with a valve on the heater line.