How accurate is everyone'* thermometer in there car. The one in my 93 seems to be off anywhere from 5 to 10 degrees at any given time. The one in my 89 seems to be accurate within 5 degrees. Also would this have any effect on how my climate control works? I set the temp at 75 and it seems like it cools it way past 75 so I moved it up to 80 and now it seems just comfortable. Does the thermometer need replaced or something else?

when you set the temp it sets the temp of the air coming out of the vents, you have to adjust it to get it to where it feels comfortable to you. If you are talking about the outside temp, you might need to replace the thermometer, its in front of the rad/condenser, you will see it if you pop the hood and look straight down.

yeah i'm talking about the outside tempearture being off.

The climate control uses both of these temperature sensors (inside and outside) plus the solar sensor on the dash to determine appropriate settings. If the outside sensor is not reading properly then the inside temp will not be set properly. 10 degrees F seems like a bit much to be off. Mine is within 1 degree C all the time.

the temperature reading also is not accurate if you're sitting in traffic on a hot day, or if you havent' been driving the car because of the heat from the road, and the heat from the radiator affects the reading. it'* only accurate when you've been moving for a while so that it gets heated to the same temperature as the air that'* passing over it.

After washing the car on a warm day, mine read minus some degrees Celcius

The outside sensor is mounted at the bottom center of the radiator support, easily visible if you look under the nose of the car. Unless it'* obviously damaged by something, I'd leave it alone.

The inside sensor is mounted behind the little grille in the upper trim plate, to the right of your gauge cluster next to the lighter. I think your problem is most likely that this sensor is covered by dust and is slow to respond. The climate control uses this sensor to measure the inside temperature so it can get some feedback and determine how much cold or warm air it needs to put out, and what its fan speed needs to be.

A low vacuum source is used to draw air into that grille and over the temperature sensor, so over time, it becomes covered in layers of dust. Try using a shop vac to snort out that little grille and improve the airflow over the sensor. (Ideally, you could unscrew the upper trim panel and remove it, so you can brush off the sensor with a soft paintbrush or something like that.)

If your outside temp reading is off, I would just replace the sensor. I know those sensors are known to go bad after 5-6 years on Chryslers and BMWs.

Okay, hang on a minute here. As I understand it, the main problem is that the car is cooling down way past the dialed-in setting of 75º:

This tells me that the internal temperature sensor, behind the little grille next to the lighter, is slow to respond (i.e. to chill down in response to the cool air inside the car). In my experience, that'* probably due to dust and dirt buildup on it, and removing the grille for a little cleaning may improve its responsiveness.

I think it'* also possible, through the climate-control diagnostics menu, to bring up a reading of what the inside temperature sensor is reporting.

As for the outside temperature being off, I wouldn't bet on that unless the display is showing you totally ludicrous readings. The location of the outside sensor gives pretty steady readings, but it might get a little thrown off by things like hot pavement, etc.

That'* not the way I read it. His original question was that his external temperature reading was 5-10 degrees off. If the exterior sensor is way off, then it will throw the entire system off.