Cadillac Repair: Heater/AC, cadillac deville, possability

Question
I have a 1997 Cadillac Deville.  Recently the heater/AC blower has begun to drop in and out.  Mostly it doesn't run when I set the temperature above ambient to call for heat.
Any suggestions as to possible causes?

Answer
Hi Glen, Sounds like the blower motor might be on the way out and it might not matter where the settings are. The other possability is the inside temp sensor is telling the blower motor that the temperature is where it is set and so it turns down the blower speed. If taking the fan speed off the automatic setting and forceing it to speed up and it doesn't, then I would suspect an intermittant blower motor or module inside the blower motor that might need replaceing. Bill