Hello, we are having a problem with my husband's 2002 F250 and I am hoping someone here might have an answer. When ever he stops at a red light or something he has to power brake the truck to keep the rpm's up so the air conditioner will blow cold. If he doesn't it seems as though the air is blowing across the heater core and blows hot air. We have put gauges on in and they read that his freon level is in the normal range. I think it sounds like a vacuum leak but since diesel's don't create vacuum it has to have a vacuum pump. Does this sound like it could be the problem and if so does any one know where the vacuum pump would be????? Need help soon or he will have the entire truck in pieces in the driveway.........
