Rear hvac help needed please

[Busman]

I have searched and worked on this for days. 2005 Tahoe Z71 78000 miles, auto HVAC controls. Front hvac works as it should. Rear heat and A/C work but cant switch from floor to ceiling or heat to cool. Both duct doors work and are free. Blower works as it should. Neither Rear actuators work. Have swapped them, the module and the Rear control panel with same results. Checked all hvac fuses that I can find. Have tried multiple reset procedures. There is no power on the brown wire at the actuator. I do not have a scanner. Any help would be greatly appreciated.

 

[justirv]

I have searched and worked on this for days. 2005 Tahoe Z71 78000 miles, auto HVAC controls. Front hvac works as it should. Rear heat and A/C work but cant switch from floor to ceiling or heat to cool. Both duct doors work and are free. Blower works as it should. Neither Rear actuators work. Have swapped them, the module and the Rear control panel with same results. Checked all hvac fuses that I can find. Have tried multiple reset procedures. There is no power on the brown wire at the actuator. I do not have a scanner. Any help would be greatly appreciated.

Watching, I have rear air, but have been fortunate so far. You should be getting some good advice soon.

 

[Joseph Garcia]

@swathdiver can provide some insight into the operation and testing of the various actuators in the system.

 

[Fless]

Perhaps one of these diagrams would help:

HVAC Systems - Automatic — 2005 Chevrolet Tahoe 4WD V8-5.3L VIN T Service Manual | Operation CHARM

Detailed repair manual for the 2005 Chevrolet Tahoe 4WD V8-5.3L VIN T.

charm.li

 

[Busman]

@swathdiver can provide some insight into the operation and testing of the various actuators in the system.

Front hvac system works as it should. Rear hvac blower works. Both rear duct doors operate normally. Heater core and A/C work. Actuators do not operate. No power on brown wire on either actuator. I have good grounds. From what I can find and from your diagrams the brown wire on both actuators is supposed to have batt voltage at all times. Looks like from your diagram should be fused on the ign 3 fuse located on drivers side dash panel. I will check this shortly. All other hvac fuses are good. Hopefully it is just this fuse.

 

[Busman]

Perhaps one of these diagrams would help:

HVAC Systems - Automatic — 2005 Chevrolet Tahoe 4WD V8-5.3L VIN T Service Manual | Operation CHARM

Detailed repair manual for the 2005 Chevrolet Tahoe 4WD V8-5.3L VIN T.

charm.li

Your diagram was the ticket I had a bad ignition 3 fuse. This is the fuse that powers the brown wire on the Rear actuators. I still cant adjust from roof to floor. So must still have a bad actuator. Got heat and air now. Just got stumped trying to find a fuse labeled ignition 3 instead of hvac or a/c. Thank all of you

 

[swathdiver]

I'm looking at diagram for yours on Charm.ii and see that the brown wire goes to instrument panel fuse block IGN3 and is a 10 amp fuse. It links to the Key on RUN it seems.

So if the engine is running and the brown wire is still dead, and the fuse is good, I'd find the next wiring diagram associated with that and go from there.