I purchased my car back in Sept 2013(will never NOT own a vette again). I had a error codes in the HVAC system of 01. Now as I would drive the car the outside air temp seem to be displaying the proper outside air temp. Once the system began to flash the error codes, then the outside air temp indicator climbs to what I believe is the inside cabin temperature anywhere from 70 - 90 degrees. Yesterday I replaced the blend door actuator. Cleared all the codes and the system is working great. No error code and the system keeps the temps just great at what ever temp I set it to. The fan actually blows now when in the auto mode. However it is about 35 degrees today, and after driving for about 3 miles the outside air temp begins to climb and levels out about any where in the 72 - 76 degree range and I think once again that is the inside air. Now I know to some this may be petty ut I would sure love the system to work the way it was design. Are there any known causes of this. I also have not yet acquired a FSM or I would not have to ask the question.

 

As a start, you can test the sensor:

http://www.corvettebuyers.com/c4_sen...formation.html

 

What year car?
Nothing in your profile either.

 

OOps my bad. This is a 1996 base model coupe. So this morning I start up the sled, set the temp to 75 and then take the kids to school in a different vehicle. 5 minutes later I am back home and ready to go to work. The outside air temp on dash is reading 21 and the car is nice and warm inside. A quick look of my phone shows area temperature at 20(so ready for winter to be over). Off to work I go. Everything is working fine. 2.5 miles later at an average of 25 mph the outside air temp shoots to 35. I assume still ok, at 3.5 miles it jumps to 68, then at 4.6 miles it jumps to 86. At this point the system is in auto and the fan is on auto. Fan is running at 10 the heat coming out the vents is hot and so no setting other than 60 will bring the temp down. Had to set fan manually as my feet were on fire. Went out at lunch time and checked it again. At startup the outside air temp shows 72 actually temp is about 34. Car had not been turned off for 3 hours. So I have not checked the outside sensor but I did unplug it. Outside air temp now shows 68 on the dash, error code of 05 shows up but not the system is working properly. a range of temp setting seems to work and the air at the air vents seems to be the right temp and the fan varies in speed. This sensor was changed out back in Sept down in florida right after I got the car. Part came from Autozone. I replaced it because of the outside air temp not showing right in Florida. However at that time I did not realize that there was a code in the HVAC system. Not sure where my OEM sensor is at the moment to change it out and they are a little hard to come by now.

 

01 code relates to air temp door motor or actuator. It is set when commanded position doesn't match actual position. Because there is no dash glove box I'm thinking it will be somewhat of a pain to replace. The actuator motors start sticking or gears strip and you tend to freeze or bake. The outside temp sensor is on right front core support you may find it easier to change from under car. The bracket is more unique than the actual sensor.

 

I replaced the blend motor door actuator on Saturday. Was a very easy replacement. The old one had a cracked gear. At this point I am sure the problem resides with the outside (ambient air sensor) that is in the air damn in front. That was replaced last Sept with a replacement from Autozone. However like I said with the outside probe plugged in the thing works fine until you get down the road a few miles and the outside air temp indicator on the dash shoots up then the system gets stupid.

 

I am going to do the resistance check when I get home(resistance may be futile).

 

So the test of the probe show maybe the probe is not good anymore. So I purchase a new one from one of the corvette sites. In the mean time the sensor is unplugged. And of course I get the error code. However this morning with it unplugged the read out showed 20 degrees and my phone said 21 and by the time I got down the road the temp on the display went up and by the time I got to work 40miles the temp was pretty much the same as the temp set for inside the car.

 

If anyone happens to read this and has any suggestions let me know please. I replaced the outside temp probe with a new one from Zips. So what happens is first thing in the morning the outside air temp read correct. And after exactly 2.5 miles of driving at about 30mph average the outside air temp shoots straight up to about 65 and the HVAC system acts supid from then on. Maybe the heater head is shot.

 

And to add, after doing some more reading I may have some broken cold soldier joints either in the heater head or the ac programmer. Guess that is my weekend task.