2001 Chevy Impala Temp Gauge and A/C Do Not Work on Occassi

Recently, my temp gauge stop working while I was driving and now, will come on and go off randomly. I read something on the net where other people have had the problem where the a/c does not work when the temp gauge does not work. I tried that when the temp gauge did not work and sure enough, the a/c did not work either. The blower worked but it did not get cold. I recently had the coolant flushed and replaced with green instead of dex-cool but the dealer said that would have nothing to do with it. Also, my air bag light stays on all the time and my back dome lights do not work. Sorry if you have answered any of these questions before.

Thanks-
Tim