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I have an '05 f250 c.c. and can only get air flow (ac or heat ) through the defrost ducts no matter what I set it on, feet only, feet & face, face only, etc.
Any ideas what might be the cause or where i might start checking ? Thanks
in advance for any help.
Defrost is default. Meaning your flap controls don't work. Most likely the vacuum pump is not operating. Check on passenger side inner fender.
Lot of topic about the failure already. On trucks with 4 WD most often front hubs leak the vacuum making the rest in-opertable.
Defrost is default. Meaning your flap controls don't work. Most likely the vacuum pump is not operating. Check on passenger side inner fender.
Lot of topic about the failure already. On trucks with 4 WD most often front hubs leak the vacuum making the rest in-opertable.
You know whats funny about that, on my dads 08 diesel, his vac line to the front hubs broke at the hub, but he never even knew it, had no problems with anything air related. Never had to go into 4x4 before we finally found the thing, replaced the fitting.
I had that problem. Check the small gray vacuum line going into the heater core controller, a small black plastic drum, a little bigger round than a silver dollar, about 2" long. Its on the passenger side, right next to the Engine Oil cap.
My 99 2 wd had the same problem. Turned out to be someone in the passenger seat had put their feet up against the fire wall and knocked the vacuum line off. It is under the dash on the passenger side. Worth a look.
Yep. Vacuum leak, it defaults to defrost for your safety. Was on a shatty road in my buddy's 05 PSD and couldn't figure out why the auto hubs wouldn't lock...then my dad being a service writer was like DUH! If you have a vacuum leak (which diesels create very little vacuum), the hubs won't lock unless manually locked and your heater will revert to defrost.
My 99 2 wd had the same problem. Turned out to be someone in the passenger seat had put their feet up against the fire wall and knocked the vacuum line off. It is under the dash on the passenger side. Worth a look.
The SEARCH worked. Found the above and checked my 99 4x4. Sure enough, there are two lines there with a joining connector (right under the glove box). A passenger had knocked the connector apart. 2 second fix thanks to the quoted post and this site. Thanks!