97 has DCC. Passenger side blows only hot air (hard but not full blast) when main on/off button is "on", even when set on A/C. Drivers side works fine. Passenger side does shut off when main button is pushed to "off". Help! Thanks.

This is a common problem involving the snych of the damper doors. Try this with the ac or heater set on high shut off the car and disconnect the negative battery terminal. Give it at least 5 minutes reconnect and start the car. If it doesn't reset try the other way with the ac/heater off then disconnect reconnect start and turn on high.. Trying to reset the damper doors. Do a search and check other procedures the one above worked for me after a couple of tries.

If it is the damper motors....

With the car running and AC on, pull/reinstall fuses #18 & 27 in the passenger floorboard. The motors should reset when power is reapplied if that's the problem.

This worked for me.

This is an easy, no cost and probably right first attempt to correct the problem. Sure it might not be the damper doors but it is the best place to start to look...
It usually is the damper doors get out of synch but sometimes it aint, so point taken, I guess.
Do you know how to access and intrepret the DIC codes? Are there any displayed? HVAC?

There are no codes displayed and I do have the 3 phone book size shop manuals and a pretty good code scanner. I will try and follow the advice given and mess with it this weekend. I will post results. Thanks.

I have the same problem with my 2000 convertible with the driver's side "face" vents working properly and the passengers side face vents blowing hot air. I will try the fixes described above and see if one of them works for me.

I also have another problem though that I'm hoping someone can help with. When the climate control is off, there is a constant hissing noise. The hissing noise only goes away if I have air blowing out of the face vents - the compressor does not have to be on, just as long as I have "face" selected and the system on, the hissing goes away.

Thoughts as to what could be causing the hissing and how to go about diagnosing/fixing the problem?

Thank you!!!!

David

Hey welcome to the forum, David!
I dont have a clue as to what would make the noise. I suggest you start a new thread on it to get the most response. The noise and lack of damper function may well be related. Best of Luck

Thank you. I think I will see if the hiss remains after I fix the left/right problem (assuming I am able to fix it). If the hiss is still there, I will start a new thread on that topic.

The system uses a combination of 3 vacuum actuators and 2 electronic actuators. The electronic control temperature, one on each side (pass or driver), the vac control the modes, or where you want the air directed.

If trying the steps above do not fix the issue, your temperature actuator could be dead and will need to be replaced.

You can remove the actuator and manually move the temp door, if the temp changes as you move it, that will tell you it is an actuator issue.

Whatever side is blowing too cold, or hot, depending on the outside temps, that is the side that is dead.

I just had to fix one of mine and another issue in my 99 Grand Prix. I hate elec climate controls because there is more to go wrong, but this car came with it. So now I know the system very well!

Welcome David! Vaccum line is my guess.

Thank you both.

OK, with regard to the temperature problem, I will first try the fuse-pulling technique and see if that corrects it. If it doesn't, I will follow your advice and check the passenger side temperature actuator. Is there a set of instructions somewhere as to where the actuator is located and how to get to it?

Same question about the hissing noise - any instructions about how to access the vacuum lines and check them?

Thanks a million guys.

Yes there is, let me pull it from my electronic copy of the GM manuals.

PM me an email address and I can send it to you in a PDF.

And your welcome!

We are all glad to help too!

Thank you!

After I tackle this problem, I can then turn my attention to the other problems that have plagued my car:

1) Fuel senders - I have had to replace either the left or right fuel sender 11 (yes, ELEVEN) times. One time the car shut down when I was doing 65 on the highway because it thought it ran out of gas.

2) Driver seat memory module - I have had this replaced 6 times. The memory feature would go haywire and send the seat to random positions.

3) Steering column lock - I finally tackled this one on my own (after GM's K-Harness failed after 6 weeks) by installing a CLB and having the computer reprogrammed to turn off the steering column lock routine.

I think I'll work on the climate control first ;-)

Thanks again.