2nd Gen Non-Engine/Transmission 97 A/C to Heat dial not working

[Got Smoke?]

Can anyone tell me why my A/C to heat dial would not be working? Its stuck on heat and won't go back to A/C... . not that I need it to during the winter but its been stuck like this since last fall.

 

[Joe G.]

The knob may be busted. Common failure.

 

[Got Smoke?]

The knob may be busted. Common failure.

Knob spins freely back and forth, but feels like no resistance in doing so. I can take a pair of pliers and turn the blend door on the bottom of the ducting under the dash by the stub that sticks out, but once I turn it back to heat its stuck there.

 

[Joe G.]

I've had three knobs fail. That's what happened each time. You may have something else wrong, but I'll bet the main cause is the knob.

 

[DieselDoghouse]

I'm confuzed (possibly genetic??) is it the temp control that's failed - a blend door controller that's cable operated OR the function knob which routes the vacuum. I've had both jam. The temp control due to cable issues, the 'mode' control when the check valves in the vacuum pump hung up (you'll also lose cruise and 4WD). Without vacuum the mode control will spin very easily with no load behind it.

 

[Got Smoke?]

Ok for kicks and giggles the other day I decided to try the knob to see if it would work. What do you know to my surprise that at first turn from full heat to full A/C the knob worked and my A/C came on. Then from that next turn from A/C back to heat it was stuck on full heat again?!#@$%!

 

[CSnyder]

UGH!!! A/C !!!!! It was a high of -9 here yesterday and you could turn on the A/C and not even feel it working! I was in my truck trying to get an idea for you but my fingers got frostbite before I got very far.



Chris