I have a cyclin creaking noise coming from the heater control area. Can you help on 1997 Buick Park Avenue

it cycles on and off in five second intervals, each cycle lasting about ten seconds, whether I have have the unit on or off. Sounds like some thing need to be oiled badly.

Asked by for the 1997 Buick Park Avenue
Most likely a heater blend door, does everything work on the heat/AC?