My 98 is having a HVAC failure somewhere in the electronics I think. It started last winter. The driver side of my dual climate control system would not blow heat. I used the defroster to heat the car so that cold air would not blow on me as I was driving. Cold air was, however, coming out of the driver side of the defroster. It worked, because the winters are usually mild in Texas and it was very mild last year. The controller began to loose it's lights long before that.

During the summer the A/C worked fine.

This winter the heater problem is back, but a whole lot worse. It began the same as last year. No heat on the driver side. I took the controller out to have a look at it. But, when I put it back in, I had no blower.

I just purchased a new controller and installed it. ($186.59 + shipping from gmpartsdirect vs $373.19 + tax from GM Dealer). It looks great. Now, I have heat on the driver side, but not on the passenger side. Additionally, the blower is either full blast or nothing. I can only get full blast when the indicator lights on the controller are full and I wait a few seconds and press the up button once more.

I was getting heat at first and then it stopped and starting blowing cold. I went through all the fuses and relays and I got the heat back. I hit my memory button on the door and I lost my heat again. I'll try the fuses again.

My question is, what part of the electronics may be causing this? Can someone give me a suggestion as to what to check next?

DreJoh

 

Well, after further investigation I found out how to read the DIC codes. I found 4 interesting codes.

99-HVAC - Heater, Ventilation, Air Conditioning
B0361 Left Actuator Feedback Short to GND
B0363 Left Actuator Feedback Open
B0365 Right Actuator Feedback Short to GND
B0367 Right Actuator Feedback Open

Each had a trailing history (H) character. Does that mean it was once a problem and its not a current (C) problem? Or, so the computer thinks.

In the first post I mentioned that after replacing the HVAC controller I had only high or no blower output. Well, I discovered that while setting the blower output, "SET" is displayed as the indicator bars are increasing. Once I get the bars to a level I want or I guess I want, I release the button. After 1 or 2 seconds "EXT" is displyed. I can then press the button once more and the blower blows at the level I set.

Has anyone ever replaced HVAC Actuators before? Is it very difficult? If not where are they located and are there and special tools needed to get to them?

DreJoh