http://www.dieselplace.com/forum/smileys/smiley1.gif I HAVE A 2004 F250 PSD CREW CAB. MY VENTS BLOW WARM AIR EVEN WHEN THE HEATER IS OFF AND THE TEMP IS THE COLDEST. HAS ANYONE ELSE HAD THIS PROBLEM? DOES ANYONE KNOW HOW TO FIX IT? THANKS

roadturtle,


I think that I have an answer to your problem. In Ford's finite wisdom, they designed the A/C to cycle the "cold air" differently for Regular A/C and Max A/C. I had this explained to me by a service manager when I took it in for some warranty work, but I have since then forgot (too many brain cell killershttp://www.dieselplace.com/forum/smileys/smiley4.gif). Anyway, the way that I remember it is that when the knob inside the cab is set to Max A/C, air is constantly being drawn through the condensor. When the knob is set on Regular A/C, the cool air in the cab is being re-circulated to keep the compressor from working so hard. This also makes the truck use air that is being 'pushed' across the condensor. When you come to a stop, or do city driving, the is no forced air going across the condensor. No air across = no heat being displaced. This is only true if, when the A/C is on Regular, you have cool air while moving, and hot air while sitting. If you have hot air while going down the road, then you have other problems. Try leaving the A/C on Max for the whole trip, and see if this doesn't solve your problem.


Another thing that might help: The EGR uses engine coolant to cool down the recycled exhaust gases. This, of course, adds heat to the coolant. I have heard that if the coolant temp gets too high, the computer will turn off the A/C (override the cab switch) until coolant temps drop. To keep this from happening, I have heard of people unplugging their EGR, which they said causes the A/C to be even colder. Of course, this should be done for "off-road use only".


Hope this helps!!!!

http://www.dieselplace.com/forum/smileys/smiley20.gif THANKS FOR THE INFO. THE PROBLEM SEEMS TO BE WHEN I HAVE IT ON DASH OUTSIDE AIR ONLY. THIS IS WHEN ITS WARM EVEN WHEN ITS 42 DEGREES OUT. IF I CHANGE THE SELECTOR TO DASH AND FEET IT COOLS OFF. I BELEIVE THE A/C IN ON THEN. WHY IS IT WARM WHEN IT DASH ONLY? THANKS

Hmmmm...that's kind of interesting. As you probably already know, the outside air setting is the "vent" setting on all the older trucks. I'm not quite sure of how Ford controls there heater and A/C split (I was a Chevy man before), but maybe some heat from the heater core is getting to the stream of outside air that is coming in. I don't know if Ford constantly circulates coolant through the heater core or not. I'll try and check on that one for you. Maybe try this:


Drive down the road (to make sure the truck is getting cool, ambient air) and turn on the vent. When the warm air starts blowing, cycle the temperature select knob from all the way cold to hot a few times and see if this doens't help. I'm thinking you probably tried that already, and if you have, then your guess is as good as mine. Check to see if something is blocking the vents that lets the cold air in? Good luck!!!!

http://www.dieselplace.com/forum/smileys/hihi.gif I droped the truck off at the dealer this morning. I asked them to change the oil, lube, and oil filter. They did the oil change. I also asked them to check the heater. They said the mechanic found nothing wrong. The service manage drove the truck, and said there was something wrong. I have to return the truck on Wednesday. Well see what they find. I'll let ya know. I also tried turning the knob, cycling the a/c. Didn't work, but thanks for the advice. http://www.dieselplace.com/forum/smileys/smiley20.gif