2003 GMC Sierra Electronic/electrical

My A/C suddenly stopped working one day. When it did, several lights came on the instrument panel (ABS indicator, Emergency brake indicator and Check Engine indicator. Also, I now only get power to one side of my trailer lights. All the fuses have been checked and are good. The blower motor is good and the speed resistor has been replaced. Also, there is no power to the passenger door accessories i.e., window button, locks, rear view mirror. The middle vent blows hot air when going down the highway and I can't roll down my passenger window! GM is well known for ineptness re: electronic/electrical performance. Please direct me.
Thanks,
Gregg Holt