Auto Climate Control Issue

[429cv23]

Just wondering if what I'm experiencing with my wife's 2004 Tahoe Z71 is a common thing.
The original ACC module was failing; typical temp control encoder modules failing.
I replaced it with a new ACC module. The new module had erratic behavior; with both sides set to same temp, intermittently one side would be blowing hot air, the other side cold, sometimes while running they'd flip flop temps. In the summer with AC running, it would sometimes just switch to full heat.
So I replaced it with another brand new ACC module. This one would only provide heat if the temps were set to 90*, and when switching from panel to defrost it would also switch to ice cold air. Sometimes when set at 90* and panel outlets, it would continuously go through the temp range from hot to cold and back, like it was hunting for the temp. I performed the calibration on both new modules numerous times. Neither new module had DIP switches on the back panel.

I sourced one from a salvage yard, and it works exactly as it should. I'll save the 'new' POS module to scavenge the temp controllers if/when the good ACC module's components fail.

 

[Fless]

Depending on the model year, some of the OE HVAC heads had updated calibrations (OS/firmware) available from GM, which corrected some behaviors.

I updated mine using TIS2000 when I had my Tech 2, and also cleaned the two pots when I replaced the backlighting.

 

[Doubeleive]

Just wondering if what I'm experiencing with my wife's 2004 Tahoe Z71 is a common thing.
The original ACC module was failing; typical temp control encoder modules failing.
I replaced it with a new ACC module. The new module had erratic behavior; with both sides set to same temp, intermittently one side would be blowing hot air, the other side cold, sometimes while running they'd flip flop temps. In the summer with AC running, it would sometimes just switch to full heat.
So I replaced it with another brand new ACC module. This one would only provide heat if the temps were set to 90*, and when switching from panel to defrost it would also switch to ice cold air. Sometimes when set at 90* and panel outlets, it would continuously go through the temp range from hot to cold and back, like it was hunting for the temp. I performed the calibration on both new modules numerous times. Neither new module had DIP switches on the back panel.

I sourced one from a salvage yard, and it works exactly as it should. I'll save the 'new' POS module to scavenge the temp controllers if/when the good ACC module's components fail.

most likely it needs to be learned to the vin. had a very similar issue after extensive troubleshooting it simply needed to be learned to the vin.
I am not sure if a tech2 alone can do that or if it needs to be done via techline, when I had this issue I was at wits end and had the dealer deal with it.
It was probably the only thing I had not tried myself.

 

[429cv23]

Thanks for the info!
It's interesting that new units will not work correctly, yet one from a different vehicle works fine.
When this one starts having issues I'll try installing one of the new ones and see if the Tech 2 will configure it or marry it to the VIN.

 

[strutaeng]

If you have that tweeter-looking thing on the headliner driver's side, check that out. I replaced that on my 06 because the temperature range didn't really work. That thing is like an ambient temperature sensor and has a little blower wheel: my wheel was seized. I posted the part number once upon a time on a different thread.

@Fless do you remember what that's called? If anything, you can remove, inspect and add a drop of oil to the part maybe?

 

[SpareParts]

I could be wrong but i seem to remember after replacing there is a recalibrate procedure you need to do for a new one.

 

[Doubeleive]

If you have that tweeter-looking thing on the headliner driver's side, check that out. I replaced that on my 06 because the temperature range didn't really work. That thing is like an ambient temperature sensor and has a little blower wheel: my wheel was seized. I posted the part number once upon a time on a different thread.

@Fless do you remember what that's called? If anything, you can remove, inspect and add a drop of oil to the part maybe?

one would think this would be the issue, but in the case of it only working at 100% it's the control unit.
On mine it was looking for a sensor I did not have, programming it to the vin fixed it.
i bought new sensors, new actuator, tore half the truck apart finding the little thermisters that are placed in the heating ducts, pulled those and ohm tested, checked with heat gun, checked voltages, recalibrated, checked the sun sensor, went to the junkyard and pulled parts to try, yada yada, all the stupid thing needed was to be learned to vin.
All because some people (previous owner) like to heavily push and twist controls so hard it wears out, I have had this thing for 9 years and have not worn a single button or control off

 

[Fless]

If you have that tweeter-looking thing on the headliner driver's side, check that out. I replaced that on my 06 because the temperature range didn't really work. That thing is like an ambient temperature sensor and has a little blower wheel: my wheel was seized. I posted the part number once upon a time on a different thread.

@Fless do you remember what that's called? If anything, you can remove, inspect and add a drop of oil to the part maybe?

Cabin air temp sensor: