91 PA Ext Temp

I have been browsing for a few weeks and decided to join today. I have a 91 Park Avenue and have an external temperature sensor that's not reading right. Whenever I turn the car on it reads in the 40's. By the time I get home after driving 10 miles it reads in the 60's.

1. Is the sensor bad or is there a problem somwhere else?
2. When it reads in the 40's does it prevent the A/C from running?

Thanks in advance.
Bill

Welcome to AF Bill! Yes your sensor is bad. It does send info to the AC controller telling it what temp it is outside. If it is reading 40 deg, the controller wonders why run the compressor, therefore, it will not allow it to come on. A new sensor cost about 15 bucks at Advanced.

And as for location, the ext. temp sensor is located behind the grille (or is at least on the '90 model). The grille screws are T-15 torx. It should be pretty easy to spot once you have the new one in hand to use as a reference as to what it looks like. :)

I knew I had a pic of that thing somewhere, here it is! :grinyes:
http://files.automotiveforums.com/gallery/watermark.php?file=/500/297374AX27.jpg (http://www.automotiveforums.com/vbulletin/%5Bimg%5Dhttp://files.automotiveforums.com/gallery/watermark.php?file=/500/297374AX27.jpg%5B/img%5D)

Thank you both for the responses. I will be installing the new sensor tonight.

I installed the new sensor, turned the car on the ext temp was reading 62 deg F. The acutal temp was more like 72 deg F. Confused I checked unpluged the sensor and plugged it back in. Duh, I left the car on. Now it shows 49 deg F. I check the codes and it is showing a 140.

1. Any thoughts on why the new sensor was still 10 deg F off?
2. Why does it now read 49 deg F?
3. What does the 140 (Driver Air Mix Motor circuit open or shorted, or not calibrated) mean?

Thanks,
Bill

You could have a bad NEW sensor, but before we condemn the sensor, let's try something else. Turn the ignition switch ON and turn you AC control to OFF. Now, turn the ignition switch OFF and disconnect the negative battery cable, then let it sit for a few minutes. Next, reconnect the battery cable, start the car and turn the AC to AUTO. Try this first and report your findings.

When I turned the ignition ON the ext temp was reading 68 deg F. The actual temp was 65 so I thought it might be fixed. Therefore I didn't disconnect the battery like you suggested.

I went out at lunch and the ext temp was still reading 68, but the actual temp was more like 75. By the time I got back to work the ext temp was reading 69.

Do you think I should still disconnect the battery?
Should the sensor be more accurate than that? I don't care if it's not exact, but I want to make sure I will have cooling when I need it.

Thanks,
Bill

yes u need to disconnect battery this will erase any codes in memory