DESCRIPTION
The flex-blade fan assembly is designed to allow blades to flex as engine RPM increases. Blade pitch decreases as RPM increases, thereby saving power and decreasing noise level. Keep fan belt adjusted to proper tension as necessary. (Scheme 1)
Many air conditioned models use a thermostatically controlled fluid fan and torque control clutch. Thermal control drive is a silicone-filled coupling connecting fan to a fan pulley, and is operated by an internal control valve. The control valve is operated by a temperature sensitive bimetallic coil (or strip) and controls flow of silicone through the clutch. (Scheme 2)
During periods of operation when radiator discharge air temperature is low, fan clutch speeds are slowed, decreasing fan speed and increasing engine warm-up. High radiator discharge air temperature causes bimetallic coil or strip to allow a greater flow of silicone to enter clutch. This increases drag between driven member and driving member, resulting in a higher fan speed and increased cooling.
Scheme 1
Scheme 2
THERMOSTATICALLY CONTROLLED FAN ASSEMBLY
- In cases of engine overheating or insufficient air conditioning, start with a cool engine to ensure complete fan clutch disengagement. Cover radiator grille to induce high engine temperature.
- Start engine and operate at 2000 RPM. Turn on air conditioning (if equipped). When radiator discharge air temperature gets hot, a fan roar will be noticed when fan clutch engages. NOTE: It takes approximately 5-10 minutes for temperature to become hot enough to allow engagement of fan clutch. While operating engine under this condition, observe temperature light or gauge to prevent overheating. If car overheats, remove cover from radiator grille.
- When clutch engages, remove radiator grille cover and turn A/C off to assist in engine cooling. After several minutes fan clutch should disengage. This can be determined by a reduction in fan speed and roar. If fan clutch fails to function as described, it should be replaced.