2006 Trailblazer Ext LS A/C & heat problem
 

A/C works great but can't get the rear A/C to work. Plus, when I turn on the heat I get cold air out of the left side vents but heat out of the passenger side vents. Please help if you know the problem. Was told that the vents might be stuck in the dash board. If so could I do the work or should I take it into a shop.

Sounds like either the blend door or the damper for the dual zone climate control (if equipped).
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A/c, heat problems
 

I have had problems with this also. The " actuator " units caused my issues. The one on the drivers side above the transmission hump failed about a year ago, then the one on the passenger side failed a couple of months ago. As the first one costs $ 63.00, I was not to upset about having to replace another. Wrong the second unit costs $ 263.00. They are very hard to remove as each unit had one screw that is obstructed by bracing for the dash board. I managed to replace the drivers side with an open end wrench. It took about 30 minutes to remove the one screw that is obstructed. On the passenger side I went outside the box and used a "Dreml" with a cutting blade and a grinding stone to notch the brace, allowing access with a nut driver. You'll have to cut more away for clearance in removing and installing the actuator.
There is also a special " tool " that G.M. produced to get the screw out. When I tried to buy one, the parts counter acted like they had never heard of it.

I diagnosed by starting the engine and running through the temperature ranges and mode settings. There are at least 4 acuators, I believe. Just watch each one individually as you run through the setting. If it never moves there's your problem. They are hard to see moving as they only move about a quarter of a turn.
The passenger side is GM # 89018365. This one allowed the A/C cold air to operate properly on the drivers side dash mounted vents and heated air on the passenger side dash mounted vents. Heating and cooling the interior at the same time. When I removed the actuator the air control door automatically fell in the cooled air position, thus stopping the heated air.
The dealerships are charging for removeing the entire dashboard, apparently to run up the labor cost.

Warning it could be the setting controls not the actuator. However if you check around you'll find the actuators are the common problem Good luck, and you can do it yourself.

A/C Knob
 

I am having a problem with the knob on my dash. Currently I can only get it to turn to 4, it will not turn to five at all. Other than that the A/C is working fine. Is this just a problem with the knob, or could something have fallen down in the dash and causing this problem? How big of a job would it be to replace the knob and/or look into the ducts behind the dash for foreign objects? Also do you guys have any links to these parts. I'm knew at working on my Trailblazer, as I usually only work on the my old jeep, but moneys a little tight right now and the wife she is a complaining :)

Chase