My first thread guys so hopefully there is some help out there. My 04 Z71 has been a good one and I want to keep in running as long as it will 393,000+ on it as of today. Here's my issue:

1. My panel lights go from bright to dim to black. Push on the dimmer wheel and it goes back to bright. From what I have read, this is a common issue with the 04 Silverado. There is a short in there somewhere. Some recommend changing the little diimmer wheel on the left of the steering wheel. What say you???
2. Here's my REAL issue. I recently replaced the compressor as well as the control head for the heat/cool. The a/c runs great for about a week and without notice, the center of the control head that displays the temperature and other info goes black. The lights on the left and right ***** continue to burn bright, but the center of the panel is black. Not only is it black, the fan shuts off. No matter what button I push, the center stays black and there is not control of anything. Here's another quirky part of this. The vents blow very cool when the truck is moving and put our no air when it is stopped. This happens when it is 85 outside. While that air flow is common, having the air come out like the A/C is blowing cool and the fan is low makes no sense. On occasion I have heard a faint sound like a fan running when the entire truck is parked and off. We have removed the control unit, unplugged it and plugged it back in. It works like a charm when that is done for about a week. At that time, the middle of the control unit goes black and I've got nothing until we unplug and re-plug the wiring in back of the control unit.. Any ideas????? Many thanks in advance...

 

There are multiple known issues with the electrical systems on these trucks. Weak electrical connections, wires that get pinched or chaffed through, and cold solder joints are just a few of the reasons for it.

GM didn’t do a very good job in designing the cabin electrical systems - some circuits pass through the fuse boxes and/or connectors multiple times, leaving several areas for problems to occur.

Diagnosing the problem must be methodical or you can chase your tail for a long time and get nowhere.

A few general checks to make are the connections at the fuse boxes on either end of the dash, at the BCM, and the connections at the steering column/ignition switch. Make sure to disconnect the negative battery cable before unplugging the BCM.

1) The dash illumination dimming is controlled by the BCM - the dimmer wheel on the switch is just an input to the BCM. Given that you can push on the wheel and the lights come back on, I think it’s likely that the switch is the issue.

Try to confirm this by “wiggling” the dimmer wheel side to side (may need needle nose pliers or tweezers) and watch for the dash lights to change as the wheel is moved.

You can also try removing the switch from its mount and shake it or lightly tap it against your palm to see if that changes the lights.

Any response to moving the switch is a good indication it needs replacement.

2) What you’re describing here sounds like a power feed for the HVAC control head that’s not maintaining adequate contact.

Focus on why the blower fan is shutting off and it’s likely you’ll find the reason for the display cutting out. I’ll try to post a wiring diagram for you later. This is an auto AC system, correct?