all you need to do is trace the black and red vacuum hoses to the passenger side fender under the hood. They go to a vacuum resivor then to the solenoid. Make sure you have vacuum to the solenoid with the engine running if so the vacuum pump is ok and the solenoid is leaking. Either plug the vacuum feed to the solenoid or replace the solenoid.Mine went out twice and I just plugged it ... all works just dont have auto hubs

My goes to defrost when i put it in 4x4. no clue

Same thing, you have a vacuum leak somewhere. I just tried swapping the vacuum pump on the top of the passenger side wheel well in my truck and it didn't fix it. I've been told to trace the vacuum lines down to the hubs, take them off and try cutting a 1/2" or so off and putting them back on. I haven't gotten to it yet, but will try that next and let you guys know if that works.

I'm having the same problem with 04 and replaced the blender door is there anymore suggestions to fix it.

Scott, did u check little vacuum pump on passenger fender? It works the hubs and blend doors. If hubs are leaking air it won't build enough vacuum to blend dash. I plugged hub port on pump, after burning out stock pump. I just lock in the hubs when I need them.

not yet cooling off its hotter than hell in south GA.

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Hey adrenaline junkie, do you have a pic of it so i can reference it

I will post a pic on my profile scott, hope it helps. . It's on left when you looking in over radiator, in front of heater blower motor

there is also a vac line that is above passenger side valve cover beside the turbo close to the fire wall that needs to be plugged in. Where in south GA you from im in Leesburg/albany

If your pump is shot it's a 15 min fix with replacement then just plug lines going to front hubs. Will make a BIG difference in cab!