Did a search with no hits, I have a 99 silverado that you have to go to max heat on the temp control before any heat comes out. Any adjustment to the cooler side just removes all heat, Also the vent control also acts goofy when switched from vents to floor or defrost. I guess the whole system has some issue. Sometime its fine…
Anyone heard of this issue?


Trey

From your description I'd suspect the contol panel not sending the right signals. So I'd say replace it and let us know. Also is your '99 a new body style or an old body style?

It's the new body style..I found this site that seems to be very similar to my problems.

http://performancetrucks.net/forums/showthread.php?t=371072

Trey