04 Suburban Blend Door Issues

[tiktok4321]

I have an 04 Suburban LT with the digital AC control unit. My vehicle will often start with all air blowing cold. Sometimes - not all the time - the driver's side will turn to hot. I've replaced the blend door actuator several times - from OEM to cheap. Same problem repeats itself. Would changing out the control unit help? I may change it anyway - the dials don't like to track properly (ie, turn clockwise and temp jumps between going up and down to random numbers). Has changing that ever fixed the blend door issue? Obviously the actuator isn't stuck. It's very capable of moving, just moves to different positions whenever it wants to.

 

[strutaeng]

There's a temperature sensor on the headliner on the driver's side that can also cause the issues with temperature working only on cold, or either hot only.

I changed it on my 06 Suburban and that problem was fixed. There's a thread here on that...Edit: https://www.tahoeyukonforum.com/threads/2004-denali-climate-control-is-only-hot-or-cold.146629/

Mine also does the knob thing where clockwise will actually lower the temperature. Mine only does it when cold. Holding the knob down while turning it slowly is kinda my short term fix.

 

[Fless]

There may also be an updated "calibration" for the control. The firmware version would need to be read by a capable scanner (e.g., Tech 2) and compared to what's available for your VIN (dealer or GM programming site).

 

[Joseph Garcia]

^^^^^x2^^^^^ As stated above, you can use a bi-directional scanner to calibrate the movement of the blend door.

 

[tiktok4321]

I replaced the temperature sensor and it didn't do anything at all. Old one was dusty but it spun well.

The blend doors all work - just don't do what they are commanded to do. It can blow hot on Driver only, but when I shut down and restart the Sub, it goes back to blowing cold air. Note that it doesn't have any in between setting. It's full hot or full cold.

 

[ccpanel]

me too.
opposite-driver side does what i tell it, pass side says do this but only blows how.
pulled bottom blend door actuator off over trans hump on pass side and manually moved door-not sticking, not an issue.
still blows hot while drive is cool.
what am i missing?
another actualtor on top of HVAC unit?

 

[Donal]

I replaced the temperature sensor and it didn't do anything at all. Old one was dusty but it spun well.

The blend doors all work - just don't do what they are commanded to do. It can blow hot on Driver only, but when I shut down and restart the Sub, it goes back to blowing cold air. Note that it doesn't have any in between setting. It's full hot or full cold.

This calibration may help. This may require the vehicle to be asleep, (not been operated for a while or first use of the day.) Driver in seat, parking brake is not depressed, Drivers door closed. Insert ignition key and rotate to the "ON' position. press button marked "AUTO." Rotate ingition key to "OFF." Driver raise hood and fuse box cover and remove 10 amp fuse labeled, "HVAC ECAS," After one minute, at least, install fuse. enter vehicle and crank engine and let run without intervention, at least 2 minutes. Rotate ignition key to "OFF" position. Restart engine and adjust controls as needed.

If still not working properly, you probably need to have a bi-diretional scanner so you can see which component is not functioning correctly.

 

[tiktok4321]

I will try that. Thank you. Meanwhile, I replaced the AC control unit and it did nothing.

 

[Chevymec]

Have you tried not going full cold on the knob? The recirculate door has a problem where the foam wears down or wears out and the actuator will go out of range and defaults to fresh air. It can't find its learned position. Maybe the blend door is doing the same.

 

[tiktok4321]

Maybe so. I’ll see about that.