Hello all! Hope someone can help with my problem. I have a 03 Chevy Trailblazer EXT with automatic climate controls. I cannot control NEITHER rear actuators on my rear HVAC system (temperature or air position). The rear fan speeds work correctly. The problem is the same when using the front control or the back seat control. I have tried to recalibrate the HVAC system numerous times but the problem persists. I took some voltage reading on the plugs that go to the actuators. The voltages are the same and don't change when changing rear temp or air position. (5V on two of the pins and 0.17V on the other three pins). I feel like it's a control problem, but I don't know what sends the signals to change the actuators positions (front HVAC control panel or Back seat HVAC control). Both rear actuators have been changed in the past due to clicking noise problems but the blower speed control module has never been changed. Any help that you can give me is much appreciated.
NEED HELP No control over rear HVAC actuators
- Thread starter TBlazin'
- Start date
- Jul 22, 2015
- 2,724
From what I recall, the rear gets its signal based on the front passenger temp selection (even though the fancier models get a 3rd control (temp up/down) in the rear of the center console).
Unfortunately, that's as far as I go - I don't use the rear HVAC, as I never have passengers there. My clicking stopped on the actuators back there, not from replacing them, but by turning down the rear fan speed to 'off'. Worked like a charm.
You get credit for using a meter, at least! (and if you need schematics, etc. - check for links under Mooseman's sig - download links are there for the factory service manuals)
Oh - and welcome! When you have a couple of minutes, make a post in the 'member intros' thread, and tell us a little bit about yourself and the EXT.
Unfortunately, that's as far as I go - I don't use the rear HVAC, as I never have passengers there. My clicking stopped on the actuators back there, not from replacing them, but by turning down the rear fan speed to 'off'. Worked like a charm.
You get credit for using a meter, at least! (and if you need schematics, etc. - check for links under Mooseman's sig - download links are there for the factory service manuals)
Oh - and welcome! When you have a couple of minutes, make a post in the 'member intros' thread, and tell us a little bit about yourself and the EXT.
Thanks so much for your quick response. So I guess you are suggesting that the front HVAC control unit is the culprit? I wish there was a way to know for sure. I'm sure that's a pretty expensive part.From what I recall, the rear gets its signal based on the front passenger temp selection (even though the fancier models get a 3rd control (temp up/down) in the rear of the center console).
Unfortunately, that's as far as I go - I don't use the rear HVAC, as I never have passengers there. My clicking stopped on the actuators back there, not from replacing them, but by turning down the rear fan speed to 'off'. Worked like a charm.
You get credit for using a meter, at least! (and if you need schematics, etc. - check for links under Mooseman's sig - download links are there for the factory service manuals)
Oh - and welcome! When you have a couple of minutes, make a post in the 'member intros' thread, and tell us a little bit about yourself and the EXT.
- Jul 22, 2015
- 2,724
No... if I were to guess, I would stick with the rear component(s) being at fault. Test the front controls / output, before loading up the parts shotgun. Time to grab those shop manuals and verify the circuit on paper. That info is a lot better than what I gave you.
If you do wind up replacing parts front and / or rear, try local junkyards or eBay (online junkyards)
If you do wind up replacing parts front and / or rear, try local junkyards or eBay (online junkyards)