Alice, my '98 coupe, has the automatic dual climate control. It worked well and I really grew to like it. However, now, unless I set it manually at 60, I only get unregulated heat.

I understand that at 60, the controller forces the temperature door to totally bypass the heater core and that at 90 (or whatever) it forces the temperature door to the opposite extreme.

So I now have a "digital heater," no heat at all at 60 (which is how it should be) and hotter than blazes at 61 or higher. Not a big deal, but sort of a pain in the neck.

Sometimes on a longer ride, she'll remember to modulate the temperature and the system will work as it should-but these instances are few and far in between and I can't draw any conclusions other than it takes a long ride.

I've got no codes, active or history. My battery is less than a year old and I don't have any battery-type issues. The outside temperature sensor failed (defaulted to 60 no matter what was going on outside,) and I replaced it and now have an accurate outside temperature.

Other than the lack of temperature control, all the functions on the dual climate controller are operational.

Any ideas or diagnostic strategies as to how I should approach this issue?

Thanks. I know there's some smart person out there who's fixed this already. I don't like blindly changing parts.

 

Is the AC turning on? I assume you have it on auto?

 

Where did you get those 60 and 90 numbers? They are not discussed in my 2001 FSM.

I have no experience in the HVAC area except for fixing displays and replacing bulbs. With that said, I just read the FSM and my head is still spinning. It will take me some more time to fully understand all the interactions. Could be the control unit. I don't know if the actuators are out of sync and cause this issue. Here are some links to try and see if actuators might be the issue.

http://forums.corvetteforum.com/c5-t...alization.html

http://forums.corvetteforum.com/c5-t...actuators.html


PS: Here is another link that involves the vacuum line for the actuators, common failure. Could test with a vacuum gauge.

http://forums.corvetteforum.com/c5-t...diagnosis.html