Ac/heater starts and stops spontaneously

I have a 1997 328i and recently the ac/heater starts and stops at its own will. I read some previous forums that could potentially be my problem regarding the blower motor resistor/final stage unit. However; the symptoms stated that the ac/heater will continue to work even with the engine turned off. Mine is not doing this. It just comes on and off and occasionally, when the ac is on and then turns off, the heater will sort of come on. Sometimes the lights stay on, sometimes they go off. Sometimes when I turn it off or reset the temp, it will reset back to the previous setting or just come back on. I sometimes have to turn it off several times for it to register. Any suggestions?