I have a 2004 Z71 Chevy Tahoe with 192,000 miles that runs great. The issue I have though is the electrical system is going haywire (no pun intended). The front A/C and heater stopped responding to the level knob, therefore doesn’t blow, the dash lights will periodically dim and go off, the horn doesn’t work when I want it to, and the A/C would sometimes blow warm air when it did work. The A/C used to work on all levels of the dial, and then over time, level by level, they stopped working; however, the back blower works well on both A/C and heater, which is operated by the overhead control knob. I open the front vents to allow outside air in, rather than recirculated air, and the air coming out of the vents is A/C air, but it only blows when I’m driving of course. Please help me! I want to have some kind of knowledge before I take it in to get repaired. Thank you so much.
It looks as though you have 3 or 4 unrelated problems. If you have an electronic control for the AC system…those go bad quite frequently. It will need to be replaced. You need a good independent mechanic to sort these out for you. Remember…you don’t need a dealer and you never need a chain shop.
More than likely the the controller. The blend door actuator may also be on the fritz with your description. As far as the lights. I would suggest that you check your battery connections are clean and tight and the same with the engine and chassis grounds. Let us know what you find.
I’d start by following @knfenimore 's ideas above about the battery connections, then take a peek under the dash to see if I could see anything weird going on, like loose or burned electrical connectors. Finally I’d check all the fuses.
Thank you everyone! I’ll find a mechanic to check these out for me. I’ll post back when I find out.
There is a blower motor resistor for fan speeds probably shot, not too expensive and not too hard to replace if you want to do it yourself. Parts store can tell you how, or google it for a video. Elecatrical gremlins can be hard to track, for the dash lights try adjusting the brightness to different levels just in case the dimmer control is frying out.