I wrote this for the RegalGS forums, but I decided to post it here too since it applies to most any dual climate control W-bodies. Note that on the first-gen Regals with DCC, the problem is most likely the control unit, not the actuator.
How to fix your dual climiate control:
Before you take your vehicle into the stealership and bend over to take it up the ass on their part and labor prices, there's a good chance that you can fix the mysterious hot-on-one-side-cold-on-the-other problem that plagues our digital electronic HVAC systems.
The problem can be caused by one of two things:
The HVAC control module itself
or
The left/right side door actuator
There's a very good chance it's the simpler, more affordable actuator. It's a black electronic module manufactured by CEI. It's entire job is basically to turn a little white knob that controls the hot/cold door. In many instances, it will do it's job perfectly for many years until one day you're stuck with hot air on one side and cold air on the other.
Mysteriously enough, this problem came up for me right after I disconnected and reconnected the battery. GM says that this can cause the HVAC control module to fail to initialize the door position properly, and will thereby need to be replaced (at the tune of around $500). I did a little searching around on this forum and found that ss4ever had the exact same problem I did, right down to the affected side.
I deciced to disassemble the car and find the problem.
This is what you see with the glove box removed. To remove the glove box, first take off the passenger side insulator located at the bottom of the instrument panel. It's held on with three christmas tree-type clips. Once it's off and out of the way, remove the three 7mm (9/32) bolts and finagle the box out of the compartment. The actuator is the black box with the white sticker that has an "R" on it. It's held on with what I believe are two 6mm screws.
The actuator unit.
Here is the unit with the cover removed. It now becomes apparent what the problem is. The larger gear that turns the knob is made of a cheap plastic that is put under an immense amount of force. It simply can't take this pressure and will finally give out eventually. This isn't a matter of "if", it's a matter of "when". If this is what your actuator looks like, you've found the problem. The part number for this unit is 16163982. It's kind of pathetic to pay nearly $100 (GMPD) for what essentually is just a small plastic gear, but this is what GM has given us. There is, of course, always Ed Morad.
I'll be heading to the junkyard as soon as I can to see if any other GM vehicles use this module (cheaper alternative to GMPD or Ed Morad). I'm assuming any dual climate control car will use this, but knowing GM, each model is probably different in some respect. I DO KNOW that the Grand Prix/Regal units are interchangable.
I'll post back with my findings.[br]Posted on: April 19, 2006, 07:56:17 PM_________________________________________________That was moved quick! Thanks!
and passenger side was hot, down to the two vents in the middle. The problem was my Low Blower fuse was blown. Hence, it is wise to check all HVAC and Blower fuses beforehand 
Originally Posted by pontiac6ksteawd
<br /><br /><br /><br />This car is worse than a woman!! 
