what causes a heater fan to work intermitently
probably a bad or shorted wire somewhere. check the wiring to the fan especially under the dash. if the wiring is good the fan itself could be going bad.
Could be internal to the motor, brushes are wearing down, check out rockauto.Com I bought a new factory replacement one for $35 as opposed to the same one from the dealer for $300
Search Buick Park Avenue Questions
Buick Park Avenue Experts