1991 K1500 AC Actuators

[tsr2185]

So I got the famous clicking 30 sec after each cycle off the ignition under the passenger dash. The temperature selector seems to work fine, blows cold and hot when selected to do so. But the vent selector has no response when going from defrost to floor, Its stuck on dash vents and the recycle air kicks off after a while. So I am assuming its the mode actuator, and not the blend door actuator that needs replacing?

Are these two parts interchangeable? The naming on the rockauto parts is all over the place. I just want to make sure I order the right part, given the information above.

This is what I was about to purchase:
https://www.rockauto.com/en/moreinfo.php?pk=7611816&cc=1050882&jsn=14557&jsn=14557

 

[SUBURBAN5]

When I have defrost on and turn to floor or another setting my blend door gets stuck lol. Mine is a 98 though. But I know the rubber gets sticky and gets stuck. Sometime I'll mess with it but hopefully not anytime soon.

 

[east302]

So I got the famous clicking 30 sec after each cycle off the ignition under the passenger dash. The temperature selector seems to work fine, blows cold and hot when selected to do so. But the vent selector has no response when going from defrost to floor, Its stuck on dash vents and the recycle air kicks off after a while. So I am assuming its the mode actuator, and not the blend door actuator that needs replacing?

Are these two parts interchangeable? The naming on the rockauto parts is all over the place. I just want to make sure I order the right part, given the information above.

This is what I was about to purchase:
https://www.rockauto.com/en/moreinfo.php?pk=7611816&cc=1050882&jsn=14557&jsn=14557

On my 98, which presumably has the same controls as a 91, the mode (vent position) and blend (hot/cold) actuators are the same. The blend door is above the heater core, the mode door by the gas pedal.

I suppose they are the same because they can both stop at intermittent points versus the recirc door which is either open or closed.

Short answer - yes, I’d order that.

Long answer - watch the notched dial on the actuator and see how well it rotates between the black lines on the actuator housing. Also see if the linkages look intact.

Notch in position indicator dial:

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Pictures of actuator position on a 98:

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[AK49BWL]

The heater boxes and actuation methods in these are the same for all GMT400s, but the actuators are NOT electrically the same between 88-94 and 95+. Physically and gear-wise, yes, but the early ones were controlled entirely by the HVAC head via feedback pots, whereas the later ones have the feedback pot circuitry internal to the actuator, with only a voltage feed from the HVAC head. If you were to find some in a junkyard, ANY of them, you can actually interchange gears between them and fix the ones you already have if you have split gears. The motor can be changed out as well if yours has gone bad. But electrically, each one (mode/temp/recirc, early/late of each) is a different animal.

 

[tsr2185]

On my 98, which presumably has the same controls as a 91, the mode (vent position) and blend (hot/cold) actuators are the same. The blend door is above the heater core, the mode door by the gas pedal.

I suppose they are the same because they can both stop at intermittent points versus the recirc door which is either open or closed.

Short answer - yes, I’d order that.

Long answer - watch the notched dial on the actuator and see how well it rotates between the black lines on the actuator housing. Also see if the linkages look intact.

Notch in position indicator dial:

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Pictures of actuator position on a 98:

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Thanks! Im currently offshore right now, and cant work on it till another few weeks. I guess I should get under there and physically see which one is making noise before I just order parts. I will check out the mode position also while im down there. Hopefully that's the one that's making all the noise, and I dont have multiple actuators faulty.

 

[Erin]

The ones on my 94 get stuck also. I ignore it because they eventually switch over.

 

[Scheitan]

On my 98, which presumably has the same controls as a 91, the mode (vent position) and blend (hot/cold) actuators are the same. The blend door is above the heater core, the mode door by the gas pedal.

I suppose they are the same because they can both stop at intermittent points versus the recirc door which is either open or closed.

Short answer - yes, I’d order that.

Long answer - watch the notched dial on the actuator and see how well it rotates between the black lines on the actuator housing. Also see if the linkages look intact.

Notch in position indicator dial:

You must be registered for see images attach

Pictures of actuator position on a 98:

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Sent from my iPhone using Tapatalk

Hi,
a bit of an old thread but if the blend door actuator (after having replaced the control unit only moves between the cold setting (11 o'clock) and the middle, is there any way to make it go all the way to hot (no warm air in Finnish winter is not ideal) or should I expect to replace the actuator as well? Given the involved disassembly, I'd be rather happy if that wasn't necessary...)

 

[east302]

I would suspect a bad actuator on that - particularly if the notched dial is slightly oscillating or making a ratcheting sound.

You can test if the panel is sending a signal by checking the voltage at the actuator connector. It should have three wires - ground, 12V and then signal. The signal voltage will vary between full hot and full cold. I don’t remember the range, but it’s something like 1 to 5V.

I would think that the odds of the actual damper being stuck are low. You could verify by removing the actuator and turning the damper by hand, but by that point you’ve pulled the actuator. For an interim solution, I suppose you could manually tape or wire the damper arm into the hot position somehow.