this doesn't make any since to , what's going is, sometimes the AC starts blowing warm air, I found out if I goose it I can hear what sounds like the damper door slamming shut, then AC starts blowing cold again. I changed out electric vacuum pump, but it still does it, starting to get worse & its hot.
Truck is a 2002 f250 powerstroke, the way I understand it, is only thing vacuum pump is supposed to control is AC & 4 wheel locks, my truck is only 2wd. I don't understand why when when I goose it ,it goes to working, what can I do to fix this, any help will be appreciated THANKS
I just found out the " heat and cool "adjustment is electrical, not vacuum, it goes to something under dash, but I have no idea what it is, heat strip, reastat(sp)??? where and what damper am I hearing. It is not like heater is on ,not that hot, feels like ambient temp, im at a loss

 

sounds like a vacuum leak of some kind....maybe a bad blend door motor....or maybe some vacuum hose under hood have deteriorated from heat....or...with truck running, would get on passenger side and move controls and listen for possible leaks...

 

I had dash dropped and could see most all stuff, but still couldn't find leak . I even took off the vacuum reservoir and tested it. I cant locate any damper that would do this, I have moved all that I can see. I'm stumped. Thanks

 

Busted temperature blend door. Extremely common.

 

Where exactly is the temp blend door & how do I get to it,
Thanks for the info, that's a start ,now to see if I can figure it out

 

It's in the dash to the left of the glovebox. You either take the whole dash out to get to it or you cut a hole into the interior panels of the dash to get to it.

I'd suggest google searches of the part, you'll find many resources for information.

 

Thanks for the replies , I think I will try and tear into today , again thanks ,I wouldn't have had any idea where to start without the help

 

I thought I found & fixed problem ,but no. it didn't work, I took electrical box off what I think is blend door ( electric control box works) I put a piece of key way in door slot & ty wrapped it closed, I took cover off heater core,so I could see what I was doing, the key way fit good & would & close door. But it is still doing the same thing, Any ideas, I need help Thanks