HVAC Blend Door issues. Control head or actuators?
 

Recently picked up an SS and have been giving it some TLC. The most recent issue I've been working on is the AC wasn't working when I got the truck. Turns out the refrigerant was low in addition to there being an issue with the HVAC controls or actuators.

I don't seem to have any control over the hot/cold actuator (top in middle of dash), driver, or passenger actuators. The recirc actuator does change position correctly but it sounds like it is constantly running towards either extreme, open or closed.

The hot/cold actuator will cycle from one side to the other at key on but then will stick to one extreme, which happens to be full heat. It also stays pushing that direction.

The driver and passenger actuators seem to just stick to one extreme and don't move anywhere else, unless an actuator is plugged in that's not at that extreme yet. They also seem to stay "running" to that side.

I have a second control head which doesn't seem to make any difference as well as two spare actuators of unknown working state. They don't change the result no matter what position they are out in.

Looking for some advice from others who have been down this road.

Re: HVAC Blend Door issues. Control head or actuators?
 

The actuators are/have been issues with these years. I think the one that is giving you the issue would be the one accessible from under the heat bopx near the passenger side of the floor tunnel. Not positive though, been a while since I had to work on one.

Re: HVAC Blend Door issues. Control head or actuators?
 

Driver blend motor is on the bottom of the airbox between the beauty cover and the heater box near the transmission tunnel.
Passenger blend motor is on top of the airbox under a plenum tube. Supposedly you can reach it through the empty radio hole.

Look in the GMT800 FAQ sticky for the HVAC controller reset procedure.
Sometimes you can get the blend motors to operate properly again by resetting the controller.

Re: HVAC Blend Door issues. Control head or actuators?
 

I've tried the controller reset via pulling the battery/fuse and I've tried it with a shop grade scan tool via the software actuator calibration. Neither worked, they run through the calibration and then just peg out to one side.

Is there a way to find out what P/N actuators are supposed to be in which location? The truck came with a couple extra actuators but I don’t know which ones were pulled and replaced with what.

I have actuators with the following part numbers: 3BIH-19E616-JA 00031691A (WOORY), 3BIH-19E616-FA 000031741A (WOORY), 52402588 C3432164Ap (CEI), 16163982 M3331483B (CEI).

Re: HVAC Blend Door issues. Control head or actuators?
 

Usually the small plastic gears strip out or split.

You can pop em open and look over the gears to see what failed.

52402588 & 16163982 are 1994-2012 GM 1500 & 2500 light truck blend door actuator part numbers.

3BIH-19E616-JA 00031691A (WOORY), 3BIH-19E616-FA 000031741A (WOORY) are aftermarket manufacturer part numbers. If they look the same as the GM parts then they likely are.

If you're blowing through actuators the blend doors may be binding up on filth inside the airbox and breaking them.

Re: HVAC Blend Door issues. Control head or actuators?
 

One does have a gear that has split but the others looked fine. They all seemed to function during a calibration but afterwards they all just peg out to one side. But like I said, using a scan tool I could see the commanded steps data from the control head and the actuator step and could see the actuators not even attempting to move.

The two part numbers, which ones go where?

If I have it figured out correctly the one located in the driver foot well is the "mode switch" for low, high+low, high, high+def, and def selection. That is one part number I imagine.

Then the passenger foot well is the temperature mix for driver side? And center upper dash is passenger mix?

Re: HVAC Blend Door issues. Control head or actuators?
 

• The motor under the kick panel on the bottom is the LH blend door motor that changes the LH cab temp from hot to not.

Attachment 2037995

• The one on the LH end of the airbox near the go pedal is the Mode door. It moves the mode flap that directs airflow out of the HVAC box to the Defroster vents, the dash vents, or down to the floor vents depending on what you ask it for.
• The motor on top of the airbox is the RH blend door motor that changes temp from hot to not. You can get to this one by removing the radio and reaching through the hole... supposedly. It's under a duct so I wouldn't count on it but it's worth a try.
• The Recirculation door motor controls the recirc flap that selects outside fresh air or recirculates the stale cab air from the RH floor area. This one is buried behind the glovebox in a pretty miserable location to access.

Attachment 2037994

Re: HVAC Blend Door issues. Control head or actuators?
 

Great pic thank you.

Re: HVAC Blend Door issues. Control head or actuators?
 

Looks like the actuators were the problem. I replaced them with cheap knockoffs and it's all working again.