Buick Riviera Forum : “1995 Riviera heater fan run all time even with car turned off.”

Sounds like the resistor block or fusible link for the blower motor has fried itself open.  

Check the relay, sometimes this relays get stuck.

Hi ,
my wife's 1993 Riviera did the same and locked the car and went to work, but the fan kept running draining the battery. These cars use a module in and or around the blower motor, this module consists of an STK Integrated Circuit that is just an IC and it is not a repairable item, only way to just buy one and replace it, this will fix the heater fan running all the time. It is also a circuit for the ACC (Automatic Climate control) relays signals to this Fan module that is how the fan automatically runs at speeds governed by the supply and demand of the system.