20 Most Recent 2004 GMC Sierra - Page 7 Questions & Answers

Could be a blend door problem under the dash.

Probably needs a good flush and new filter

your engine is getting to hot. either your low on coolant, your thermostat isnt working properly, or you radiator fan isnt coming on

Sounds like the blend door. The actuator motor is located on top of the box (behind the glove box) and is notorious for failing.

Hi J, The ground connections are on each of the units. that is to say there is one power feed to the dome and another to the instrument panel. From there each door is separately grounded via each of the door switches. If one is rusted, contaminated or damaged and not operating correctly, it will cause the dome light and the door warning on the instrument panel to flicker. regards John

When the compressor kicks on, is the air from the vents blowing cold? If the air isn't blowing cold, then your problem could be that you may have water in the system. I had a '93 Chevy Z71 that wouldn't blow cold and thats what my problem was. System needs to be evacuated and refilled. Good luck bro.

http://www.youtube.com/watch?v=I5xfVyb_p9A

This is definitely the Relay which is part of the Blower Motor Resistor Module. The Engineers designed it to FAIL when the Return Spring breaks. The Relay Contact is only utilized for the Highest Speed, The armature (Movable Contact) makes connection due to gravity when the Spring Fails. The Relay is mounted UPSIDE DOWN and was designed into the module that way. It is not independently serviceable!

Take it from me as my 2004 Silverado has gone through 3 Resistor Modules and 1 Blower Motor. Michigan winters are relatively cold!