Well, on my old '96 Ford, I installed a simple brass ball valve on the heater hose going to the heater core. I'd close this valve for the warmer months keepin the vent cooler and the A/C colder.

Think this'll work on our new CTD's ????

 

As long as you isolate the heater core, it should. I've done it on a number of big trucks, but I always put a valve on the return line also to keep the hot water from migrating up it.

 

Great Idea, if I can't get the A/C on my Mega Cab fixed (4 months now) I am going to market a kit and sell it on Ebay!!! The only problem is with the blend/recirc door problems you pull ambient air.

I pinched off my heater core hoses and still had warm air on the right side, just can't win on this crappy design.

Silverbullet06

 

Bob Riley sells a kit for the Ford Superduty trucks. I have one on my ford dually. I don't remember exactly how it works, but it wont let the water circulate through the heater core when you have the vent set on max a/c.