Stuck on defrost

01F350PSD4x4 · Feb 21, 2006

My 01 will stay on defrost even if I turn the dial to other settings. It doesn't matter if the blower is on low or high, all that I get is defrost. Someone once mentioned it was caused by a vacum leak. Not sure if this is correct of not. Has anyone else had this problem? With the temps in the 20's and 30, using only defrost to heat the truck in the morning isn't a lot of fun! Thanks for the help.

GrampyJim · Feb 21, 2006

Yes, it is most likely a vacuum leak or a bad vacuum pump. Defrost is the "default" position for the HVAC system.

97PSDChaseN · Feb 21, 2006

mine did this the DAY i got it out of the shop. instead of turning around and taking it back to my dealer for another 2 weeks, i went home, got on here and started asking. what i found was a loose connection on the pass. side beside the condensor on top of that little black box.

maybe this is your problem?

-Chase N.

Raymondb · Feb 22, 2006

[ QUOTE ]
mine did this the DAY i got it out of the shop. instead of turning around and taking it back to my dealer for another 2 weeks, i went home, got on here and started asking. what i found was a loose connection on the pass. side beside the condensor on top of that little black box.

maybe this is your problem?

-Chase N.

[/ QUOTE ]

I discovered just this afternoon that my truck has the same issue. Does anyone have a schematic of the vacuum system on these things?

Tracking down vacuum leaks is a major pain, from my past experiences.

Chase, do you have any pics?

plainredtruck
who just wishes he had PMS, when in reality he just has a hobby - working on TDT (that darned truck!)!

Mrit · Feb 22, 2006

Check your fuses. Mine blew out at random one day, replaced the fuse and it has worked ever since. Several people have posted the same problem since that time and all of them have had it be their fuse.

Raymondb · Feb 22, 2006

[ QUOTE ]
Check your fuses. Mine blew out at random one day, replaced the fuse and it has worked ever since. Several people have posted the same problem since that time and all of them have had it be their fuse.

[/ QUOTE ]

As if electrical issues are any more palatable /ubbthreads/images/graemlins/shrug.gif

Good idea, and I'll go check it out.

plainredtruck

Atlantaboy · Feb 22, 2006

my 01' did the same. It was a leak at the pump and a loose hose.

Raymondb · Feb 22, 2006

[ QUOTE ]
my 01' did the same. It was a leak at the pump and a loose hose.

[/ QUOTE ]

TA-DA!

It's more than a loose hose. The dang thing's been chewed in half! Some critter's been nesting in an old rag I had stuffed under the blower motor and must've decided plastic was tasty.

Now I just have to figure out where it belongs.

Still hoping for that schematic . . .

Pictures tomorrow.

plainredtruck

Raymondb · Feb 22, 2006

As promised, photos are here:

vacuum hose

PRT

On edit: I would appreciate if someone could take a look and tell me where the hose should be attached. I'm getting replacement line tomorrow.

Thanks.

Stuck on defrost

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