I have an overhead display that shows the outside temp. It shows the correct temp and is constant. Could it still be the sensor up front by the radiator? I also noticed that if I depress the Fresh Air button that it flashes three times then turns off. The same thing is true for the A/C.

 

mine is the same did you find a fix?

 

No, not yet. The local dealer said that they would diagnose the problem for $90. I am still hoping someone will come up with something. If I do I will post the resolution for you.

 

engine temp sensor and or coolant temp sensor.

 

Sorry this doesn't help the rest of you guys having this problem but the wife said the heck with it and we traded it in for a 2007 program Trailblazer. Good luck though.

 

Anybody have an answer to this yet, I am having similar problems. 99 Blazer had the heater core replaced in Jan 06, last fall the ac only blows warm, compressor does not cycle on, thought maybe the compressor died. Then during the winter the heat would not blow hot for more than a few seconds then go cold. So basically I have no heat in the winter and no ac in the summer. I can live with it but now with a new baby she can't. Any ideas would be helpful. Thasnks