I recently replaced the intake gasket and had Sears put a new battery in my 99 tahoe. I don't know if either service caused my most recent problem.

The heater fan control switch seems to have the positions all mixed up. switch off - fan running on step 2 or 3
1st position - fan on high
2nd and 3rd position - fan on low
high position - fan is off

AC works and temp dial works ok, just the fan switch is messed up?

Anyone have any ideas?

We had a simular problem on my 99 Tahoe. The AC has a mind of its own. Off would be on. The dealer replaced the control switch assy under warranty at 75,000 miles. AT 107,000 it occasially does in the off position.

Maybe it's another one of those components that are cold soldered, like the harness part on the wiper moter mother board that everyone has problems with eventually.

When my wipers got a mind of their own I looked at it. At first I couldn't see anything wrong, but when I looked at the 4 points that are cold soldered real close they were all broken, but still touching. It was easy to get at and re-solder though. Works like new.