Electric Engine Cooling Fan Assembly. Buick Roadmaster 1996

For 1990-2009 cars

### Engine Cooling Fans

An electric engine cooling fan aids air flow through the radiator and the A/C condenser. The base cooling system has 2 electric motor driven fans mounted on the rear face of the radiator. A 150 watt motor drives the right-hand fan, and a 100 watt motor drives the left-hand fan.

The extra capacity cooling system (RPO VO3) replaces the left-hand fan motor with a 240 watt motor. The heavy-duty cooling system (RPO VO8) replaces the right-hand fan with a belt-driven engine fan, controlled by a thermostatic fluid clutch. A fan motor with a 240 watt motor replaces the left-hand fan motor.

### Fan Blade Clutch (w/ RPO VO8 Heavy-Duty Cooling System)

The engine drives the fan blade through a silicone fluid drive fan blade clutch. The silicone driving fluid allows enough slippage to limit the maximum fan blade RPM. In addition, the clutch eliminates overcooling, excessive noise and power loss at high speeds.

The clutch contains a thermostatic coil that senses the temperature of the air taken in through the radiator by the fan blade. When the temperature of this air falls below approximately 66°C (151°F), the clutch limits the fan speed to between 800-1,400 RPM. When the temperature of this air rises above approximately 66°C (151°F), the clutch will allow the fan to increase to a maximum speed of approximately 2,000 RPM. Do not disturb the calibration of the clutch because the clutch is calibrated at the time of manufacture.

Under certain temperature conditions, there is a lateral movement at the fan blade tip that should not be considered as hub or bearing failure. This condition is a clutch design feature which allows up to approximately 6 mm (1/4 in) lateral movement, measured at the fan blade tip.

Testing a clutch by holding the small hub with one hand, and rotating the aluminum housing in a clockwise or counterclockwise motion, causes the clutch to freewheel. This is a normal condition when the clutch is operated in this manner. However, this is not a test for clutch replacement.

### Cooling Fan Relays

Relays, controlled by the Powertrain Control Module (PCM), activate the electric, motor-driven cooling fans. In order to determine electric cooling fan operation, the PCM senses the following conditions:

• | Cooling system temperature

• | Vehicle speed

• | A/C high-side pressure status