'94 2500, AT, 5.7L v8, PB, PS, Ext Cab, AC, etc...

When I turn the truck off / on, somehow the setting for the heater control system gets reset to:

Fan = Low
Temp = Mid range between blue and red.

Even if I have the AC ON and Fan set on high, it some times gets reset. Not all the time, only sometimes.

Same if I have it OFF, sometimes it gets reset to Fan = Low and temp = midrange.

This is annoying. Why is it happening ?

Same thing was happening with my 92 full size chevy, then it finally went dead. Brought it to my local garage and then found some chaffed wires behind the dash. Most likely the wires were rubbing on an aftermarket radio unit I installed a couple of years ago.

Good luck