99.9% sure our HVAC controller is dead

[skylark]

I have been putting this off for awhile now and it is starting to get a little cold here. On our 2000 K3500 the defroster and recirculate functions don't work. I had to change the heater core so while I had it apart I checked that the mode doors weren't stuck. I could move them manually but I could only get it to change with floor and vent not my defrost. I would've called it good at that point but I noticed that when I turned the knob to defrost I could hear the A/C clutch cycle. I re-soldered all of the connections and didn't have any luck. I'm hoping that there is a second set of contacts that are engaging the A/C clutch. I believe that I will bit the bullet and buy a new controller unless someone has some insight as to what else may be going on.

 

[1997chevydriver]

a/c clutch cycling in defrost is normal.

 

[skylark]

a/c clutch cycling in defrost is normal.

I was aware of that and that is why I am wondering if there are 2 sets of contacts in the switch, one for the clutch and one for the mode door.

 

[1997chevydriver]

I was aware of that and that is why I am wondering if there are 2 sets of contacts in the switch, one for the clutch and one for the mode door.

oh my bad I thought you were thinking something was shorting out inside to make the a/c come on.

 

[skylark]

No worries! Always a good idea to check.

 

[outalne94z71]

usually the switch does not go bad, the encoder motors do

 

[skylark]

usually the switch does not go bad, the encoder motors do

I would think that as well but I can see the motor operate for the floor and vent positions.

 

[skylark]

FIXED IT!!!
The defrost didn't work when we bought the truck last March. It turns out that the problem was that a previous "repair" was done incorrectly. There are 2 spring loaded linkages that operate the various doors and those linkages are connected to the encoder motor. One of those linkages must have come apart and someone put it back together incorrectly. If you put the linkage together on the opposite side, instead of sliding like it is supposed to, it hits a dimple and stops essentially making the linkage solid. I put together correctly and it works. I'm a happy camper!!!

 

[outalne94z71]

FIXED IT!!!
The defrost didn't work when we bought the truck last March. It turns out that the problem was that a previous "repair" was done incorrectly. There are 2 spring loaded linkages that operate the various doors and those linkages are connected to the encoder motor. One of those linkages must have come apart and someone put it back together incorrectly. If you put the linkage together on the opposite side, instead of sliding like it is supposed to, it hits a dimple and stops essentially making the linkage solid. I put together correctly and it works. I'm a happy camper!!!

i had those come apart on my old 94 before, little bit of a drag getting them back together