Only drove around for a little while and noticed that it was stuck on 34 degrees. It's about 48-53 degrees out right now.

Any potential problems here?

 

Depends on how far you drove. After starting the car it takes a couple of miles before the temp resets from a prior reading. Usually if the temp sensor fails the external temp readout defaults to a 69 degree reading.

Bill

 

Yes the outside air temperature module is corroded.

It is located in the front passenger area of the nose of the car. It looks like a plastic nipple looking thing.

I think you can find many posts here regarding how to replace it. I would suggest you search for the module where stated and attempt to unplug it. You may end up needing a new wire harness like i did that cost 40 bux. Check if the wire connectors are stuck on the plug wire adapter side. My temp sensor connector wires broke off in the female side connector

 

They fail and stay at many different readings not just 69 lol

mine read 34 when it failed

 

Hi Charlie -

You have to have the car rolling for more than x number of seconds before the temp gage will start updating the temp display as BIll mentions.

When the sensor went bad in my wifes 99 coupe, it would read much lower than the abient temps in the summer, and thus the HVAC would not work.

GM used the same sensor on several different cars, and most dealers will have the part in stock - for under $10.

It is a quick snap-in r&r and it sure is nice to get the proper temps displaying again (and the HVAC back to operational).

best regards -

mqqn

 

Here is the description of sensor operation and displays shown upon start from the 03 Service Manual:

Air Temperature Sensors
The air temperature sensors are a 2-wire negative temperature co-efficient thermistor. The vehicle uses the following air temperature sensors:

Ambient air temperature sensor
Inside air temperature sensor
A signal and low reference circuit enables the sensor to operate. As the air temperature surrounding the sensor increases, the sensor resistance decreases. The sensor signal voltage decreases as the resistance decreases. The sensor operates within a temperature range between -40 °C (-40 °F) to 101 °C (215 °F). The sensor signal varies between 0-5 volts.

The input of the duct sensor temperature is different from the ambient and inside sensors. The HVAC control module converts the signal to a range between 0-255 counts. As the air temperature increases the count value will decrease.

If the HVAC control module detects a malfunctioning sensor, then the control module software will use a defaulted air temperature value. The default action ensures that the HVAC system can adjust the inside air temperature near the desired temperature until the condition is corrected.

The driver information center (DIC) displays the ambient air temperature value that it receives from the HVAC control module through a class 2 message. The scan tool has the ability to update the displayed ambient air temperature. The ambient air temperature value is displayed or updated under the following conditions:

Condition=============================== =====Display

At start up with the engine off more than 3 hours======Displays real-time temperature

At start up with the engine off less than 3 hours=======Displays last stores temperature

Vehicle moving above 26 km/h (16 mph) for 1.5 minutes==Displays real-time temperature

Vehicle moving above 72 km/h (45 mph) for 1 minute====Displays real-time temperature

Bill