20 Most Recent 2000 GMC Sierra - Page 7 Questions & Answers

You would need to find out if the compressor continues to run when the cold air stops.

Could be wiring/cable connection issue. Take it to mechanic. Before that gently but with moderate force bang on the dash if can engage.

Should be in the fuse box near the battery.

I am at a loss knowing what gear box your referring to and if the rumbling noise began before or after changing the box. There are many things that could simply be loose underneath a vehicle. A wheel bearing can definitely make a rumbling noise. Sure you changed the right one. Can be hard to tell which one sometimes. Sorry I couldn't help more than I did.

need more info<noise there only while driving<whith foot on clutch or off clutch speed when noise loudest etc

Usually a sign you have a blend door that is stuck, or the controller has failed. The blend doors use small electric motors controlled by the main controller on the dash.

beleive there is a junction box on those models that main tail lights harness comes too then is distributed out in seperate smaller harnesses.

On most models the sensor is on the back of the intake near the firewall.

The Actuator is not functioning anymore, check to see if there is a fuse for it first. If that is ok then remove the actuator and test it outside using some wire and your car battery to see if actually moves or doesent this will tell you if you need a replacement.