HVAC control module blinking selector

[issacc1]

Hello all, I have a 1992 GMC k1500. I’m currently having trouble with my HVAC control module. When I try to select a mode or temperature, all the arrows start blinking simultaneously. This only started over the weekend. I’ve already changed the blend door actuators on the driver side and in the center. The one on the passenger side has been disconnected for as long as I’ve had the truck.

Could anyone point me in the direction of what to check next?

Attached is a photo for reference of what is happening.

Thanks in advance!

 

[GoToGuy]

There is something in the service manual about flashing indicator. Have looked the OE service manual?

 

[FrankieD61]

When I had this, on my 91, I referred to the service manual to get the error code encoded in the blinks. Number of blinks equals a certain error. MOST of the time it seems to circle back to a blend door actuator stuck or completely broken. Could be something with AC, too. So test and troubleshoot.

 

[FrankieD61]

Hello all, I have a 1992 GMC k1500. I’m currently having trouble with my HVAC control module. When I try to select a mode or temperature, all the arrows start blinking simultaneously. This only started over the weekend. I’ve already changed the blend door actuators on the driver side and in the center. The one on the passenger side has been disconnected for as long as I’ve had the truck.

Could anyone point me in the direction of what to check next?

Attached is a photo for reference of what is happening.

Thanks in advance!

You say you changed the actuators. Did you make sure to clock them the right way or index them (don’t know the proper term) but I had the same issue and was like wtffff. Then I figured out it was getting bound because the HVAC module though the door was in one place and the door was actually in another and things were getting forced to go into places they shouldn’t be so it puked.

 

[issacc1]

I have made sure that the actuators were clocked the correct way when installed. I replaced the resistor and resistor connector sine it was me slightly melted. I even tried connecting the actuator without it being connected to the linkage and I don’t see the actuator moving at all when I change the mode.

The only thing I found in the manual about blinking is which actuator is bad for the blinking indicators.

Any help would be great. Thanks!

 

[AK49BWL]

Does the motor in the actuator activate at all? You should be able to feel it and hear it if it's running the motor. If it is and nothing is moving then the gears are stripped or broken. Replace the actuator. If the motor isn't even trying? It could be the actuator or controller. Try a known-good actuator and see if it's the same. If so, control head becomes highly suspect.

 

[FrankieD61]

The thing with that system is, if there’s a fault, usually of any kind, the actuators won’t do anything when you press the buttons to control them. Atleast in my case that’s what I witnessed. Hop on eBay and get a new control head for your year. If you have good electronics/soldering skills, you can reflow the solder joints on the control head which may or may not work. In my mind it’s so worth it because I hate tossing old electronics that have the potential to work perfectly fine with a little love.

Once you shotgun that at it, I think it’s time to start chasing down wiring faults. Use the error code provided by the control head, isolate the actuator control circuit that it’s telling you is at fault and start looking for bad wiring for that portion of the system.

 

[AK49BWL]

The thing with that system is, if there’s a fault, usually of any kind, the actuators won’t do anything when you press the buttons to control them. Atleast in my case that’s what I witnessed. Hop on eBay and get a new control head for your year. If you have good electronics/soldering skills, you can reflow the solder joints on the control head which may or may not work. In my mind it’s so worth it because I hate tossing old electronics that have the potential to work perfectly fine with a little love.

Once you shotgun that at it, I think it’s time to start chasing down wiring faults. Use the error code provided by the control head, isolate the actuator control circuit that it’s telling you is at fault and start looking for bad wiring for that portion of the system.

That may be the case after it faults, but I think at first power up, it tries to function normally for the first ten or twenty seconds before entering fault mode again. Might have to pull the HVAC battery fuse to reset the controller.

 

[FrankieD61]

That may be the case after it faults, but I think at first power up, it tries to function normally for the first ten or twenty seconds before entering fault mode again. Might have to pull the HVAC battery fuse to reset the controller.

Yes yesss. Very correct you refreshed my memory .