What causes heater/ac to come on by itself and gauges go on and off.

I did find out that it is probably the cluster board. hope that helps.

Changing the ATC (automatic temperature control) will clear all of these problems. it is a known issue that the guages, lights, radio, temparature are operated by the box. When the box is replaced all will clear up. I did this 4 years ago and have not had another problem.