2000 Buick Regal A/C Controller Question

I have a 2000 Buick Regal 3.8l. The fan for the cabin air stopped working. I replaced the resistor. It worked for a while and stopped again. I replaced the fan motor. It started working off and on. I replace the A/C controller in the dash. It works most of the time now. However, on occasions the fan stops along with any other feature in the controller such as rear defrost. It doesn;t matter if the AC is on or not the power seems to disconnect. I am thinking it is one of the relays under the hood but don't know what to check next.

Thanks,

Richard