1995 Buick Lesabre A/C Problem

I just bought this car and the air conditioner works great. Now we have a cold front and when I try to use the heat the only way I can get it to work is to turn the temp to 90. If it is turned down it starts to blow cold air. The ext temp on the display is showing high numbers like 130 or 140. The car has the digital controls and the auto feature. I beleive it may be in the climat control box that is mounted behind the glove box. I was wanting to make sure this is the problem before ordering the part since it is about 500 dollars. If it is the part does any one know the best way to remove it. I had the glove box removed the other day and part of the lower dash lose and could not really see how the control box came out. I can unplg the control box and the ext temp will read right for a few seconds then go back to reading wrong. Any help on this issue will be greatly appreciated.

If your external ambient temp sensor is reading 130-140 deg on the control display, it is trying to adjust the system for that ambient temperature, therefore, no heat should be allowed, unless set at the default high temp (90 deg).:yikes::newburn:

You need to replace the ambient temp sensor first. Standard motor products part # AX27 or ACDELCO Part # 1571823 {#16169194} {ambient air temperature sensor} Cost 15 bucks at Advanced. The sensor is located in front of the radiator (grill area) and looks like this: Click Here (http://info.rockauto.com/SMP/SMPDetail3.html?AX27.html)

BTW, Welcome to AF!

Thanks. I will try that. You may have saved me alot of effort and money. I will let you know the results. Hopefully I can get this done this weekend.

Sorry for such a delay on replying, but I totally forgot about his till today. I did get the part and the unit seems to be working fine. I guess I will know more when winter gets here to see if the heat works, but atleast now I do have the correct outside temp and the auto feature works right.