Passenger side air blowing hot air when AC is on and cool air when heat is on

[Hammerhankinson]

I have a 1999 Buick Park Avenue and my passenger side climate control is behaving backwards. When the AC is on it blows hot air and when the heat is on it blows cool air. I've also noticed a non-stop squeaking noise that comes from behind my dash temp control, like something is trying to move but is stuck. Moving the passenger side climate control slider does nothing also.


From the research I've done I've found this to be a common problem and the suggested fix is to replace the passenger side air mix or blend door actuator except I've noticed that people asking about this issue have it with either just the heat OR the AC, no one mentions that it happens both ways. Is this still the suggested fix if its distributing the opposite air on both heat and AC? This is a $130 part at so I'd like to try everything to pinpoint this issue before buying the part.

 

[Spriteman]

You might try recalibrating the actuators first before you spend a bunch of money on new ones.

Turn the Key to the On position but the Engine is Off - otherwise known as KOEO.

Leave it there for 5 mins - that will allow the computer to take each actuator through each of the 255 positions that they have.

You should hear the actuators moving during this routine.

Then - just turn the key off and then start the car and they should be back in their normal position. That may be your problem and maybe not but it's at least worth a shot.

Let us know if that does the trick.

 

[Hammerhankinson]

This did not work. I did hear the actuators moving and the squeaking noise was also still there. Funny thing about that is the passenger side actuator is on the right side of the heater box but the squeaking noise seems to be coming from the left side yet the drivers side air is working properly. Could it be the mode door that is stuck?

 

[mojo117]

I recently did the same work on my '99 PA, but for the driver side. The driver side HVAC actuator motor was kaputt and only hot air would come out of that side, although the week before it totally failed, it would only blow cold when I had on the heat. I found a discussion of the subject on this site, printed out the directions, bought the part at Advance Auto Parts (with a coupon I got at retailmenot.com, it only cost about $100), and went to work. It took about 30 minutes to fix and worked perfectly afterwards. Do find the other discussion on this site that has the procedure and pictures. Good luck.

PS: The actuator motor for the mode door is on the left side, as you suspected by the squeaky noise you're hearing. Mine works and the modes change fine, but it still does make a squeak noise as it's working itself between modes. If your driver side switches modes (floor, dash, defroster vents), the mode would be working fine and should work on the passenger side, too, once the pax side actuator is changed.

 

[Spriteman]

There are two actuators on the drivers side - the Mode actuator as mentioned and there is another Temp or Blend Door actuator as well.

The squeak could just be coming from the door that's moving and not the actuator itself. If you can get up under the hush panels on both sides you'll be better able to see if the motors are actually moving the doors.

 

[Hammerhankinson]

The curious thing about the squeak is its continuous. It'll squeak for a few seconds and then stop, and then squeak again a couple seconds later then stop and repeat over and over while the car is on, even in KOEO mode. It sounds like something is trying to move but is stuck. Either way though I'll get under it and see if i can't get a better look.

Also, I don't know if that has anything to do with it but sometimes the digital temp gauge on the climate control center also goes almost completely dark when i start the car too, in the research I've done that points to the head starting to go bad. Might that be related?

 

[Spriteman]

Once you're under there - you'll be able to rotate the actuator linkages by hand. Moving them should allow you to tell which one is the noise making culprit.

 

[bigsky]

The curious thing about the squeak is its continuous. It'll squeak for a few seconds and then stop, and then squeak again a couple seconds later then stop and repeat over and over while the car is on, even in KOEO mode. It sounds like something is trying to move but is stuck. Either way though I'll get under it and see if i can't get a better look.

Also, I don't know if that has anything to do with it but sometimes the digital temp gauge on the climate control center also goes almost completely dark when i start the car too, in the research I've done that points to the head starting to go bad. Might that be related?

The actuator that keeps cycling...is a flaw of the actuator. I had that problem in the 99 PA and replaced both the driver & passenger side blend actuators. There is an "updated" actuator that is available; can search ebay and read the descriptions. Often described as the "cricket" sound. Maybe most of these blend actuators one can buy today are the new version?

For the dark climate display, if you feel comfortable taking the unit out and opening it up, there are probably some loose resistors that need re-soldering.

 

[jase386]

Do find the other discussion on this site that has the procedure and pictures. Good luck.

.

is that "good luck " for finding the article you mention? Not finding it here. Could you post a link?

 

[Spriteman]

Check out the two sticky threads on top of the Lesabre forum.

 

[G-353042]

My 1999 Buick had ac they put in Freon and no cod air. Then in winter had radiator and then replaced heater had hot air from driver vent cold from passenger vent. Was told prob blendircdoor however dashboard has to be torn out ???