97 Lumina LTZ Dual Zone Climate Control Issue

[bigbandguy]

I am having a problem in that the passenger side vents will blow hot air when the dual zone is set to cold. The drivers side vents are fine. I have been reading on the forums that it is probably the actuator on the blend doors that is causing the problem. When I goto gmpartsdirect.com there are two choices for actuator and I'm not sure which one is the one I want. There was also an AC-Delco part number 15-71846 posted for a 98 LTZ, is this the same part?

[richtazz]

there are 2 on your car with the (CJ3) dual zone A/C, one for passenger side, one for driver side. They are both the same part number (AC-Delco #15-71846)

[bigbandguy]

Thanks for the info. Here's what I've done. I pulled the blend door servo and it seems to work O.K. by applying 12 volts to the motor. There are 6 pins (# 5 thru # 10 ) where the harness attaches to the servo block and pins # 5 & 6 will work the motor (forward/reverse - by switching) but there is an on-board card that must have some positioning control and I couldn't figure out how that functions. The wiring harness has a power wire (brown) and a black (ground) and a white/black which is connected to the slider. These are connect to pins #7,8 & 9 respectively - I think.

When I try and operate the servo using the passenger dash slider it will not change position. I could see it try to move when I move the slider but it will not rotate. From the Haynes wiring diagram it appears that the slider is a "rheosat" so it must move the motor and in turn the blend door but it appears only over a maximum 90 deg. The on board "circuitboard" must have some smarts to tell the motor when it has achieved its proper position.

My problem is what is malfunctioning the dash mounted controller or the servo device or something else?

I was trying to use the driver's side slider to see if it would work since it works fine on the driver's side but it is a challenge to try and jumper the wiring harness to make that happen and I couldn't seem to get anything to happen.

The dash unit is available and is about $ 250 and the controller about $50. It would be nice to know through some kind of testing which one or maybe if neither is the problem.

Thoughts, comments?

[richtazz]

if the drivers side works, try switching the actuators around. If the drivers side still works, the control head is bad. If the passengers side starts to work and the drivers quits, the actuator is bad. The actuators are both the same part, so they are interchangeable.

[bigbandguy]

Update:

It was the heater/A-C controller. I managed to find a used one from a '99 and it seems to work................

Another related question....................some of the lights in the radio face aren't working? Are they replaceable? How does one go about it?