F250 Turn off the heat!

I don't know about this vehicle, but some vehicles use vacuum or a cable to control the positioning of the "blend door". The blend door allows or inhibits the flow of air from the various sources. Perhaps on your truck even when you turn the knob on the dash to "vent" it is still including air from the heater core. On second thought, on my truck ('93 F-150) I am supposed to get heat if the selector is on 'vent' and the temperature knob is turned to heat. Maybe you just need to turn the temperature knob down a bit? (hey - it's work double-checking! :-))

-D

Might help/might not. The Temperature blend door might be out of adjustment or just not closing properly. These blend doors have the nasty habit of breaking from the hinge and are a 'bear' to repair. Check the adjustment cable to make sure the door is actually shutting completely. Even if you 'short out' the hoses, you will still get hot air through the vents....it's hot both outside and in the engine compartment.

Dave S(Texas)

Respectfully, In Texas it's always hot this time of year ;-) In Connecticut we often have 70 degree days when I would just a soon run with window open and the vents on the cool setting. I was wondering if any harm would come buy "shorting out" the hoses nor putting a ball valve in one of them to stop the flow during the summer. In some of my older cars, a slight flow was desired for bypass purposes.

Pete

If you are still 'on' the original core, I'd just seal it to be air-tight, after draining it. Cores don't last much more than 10yrs and yours is getting 'to that point'. If it's been changed recently, I'd be sure to fill it with some type of corrosion inhibitor and then seal it. I wouldn't consider some type of flow restrictor. Doing that would just cause a presssure build-up in your cooling system which might be a cause for problems. The first time I had to bypass my core, because it was leaking, I used a piece of copper tubing and two clamps. Worked just fine!

Dave S(Texas)

Known issue with my vintage (2000) PSD...way too much heat in summer - coolant always flows HOT thru core....here is what a LOT of us have done to add cooling : Purchase hose barbs (brass or Stainless) and hose clamps in the correct diameter. Acquire ball valve in correct size. Cut the heater hose that leads to the core (will heat up first and be warmer) in a convenient location. Install valve w/ barbs. When it's warm out to the point where ya don't need heat, close the valve....much cooler interior! Every now and then I open it to flush the core....

Lots of posts on this at

Thank-you for the info.

Pete

If it has A/C then it has a heater control valve. Perhaps it's bad and letting some hot water by.