THERMO Control Fan: Testing
- When engine overheating or insufficient cooling by air conditioning occur, fan drive and thermostatic control must be tested. Start with cool engine to ensure complete fan drive disengagement. Cover radiator grille sufficiently to induce high engine temperature.
- Start engine. Operate at 2000 RPM and turn on air conditioning, if equipped. Fan noise will increase when fan drive engages. It will take 5-10 minutes for fan to become engaged. While operating engine under these conditions, observe temperature light to prevent overheating. If hot light comes on, remove cover from radiator grille.
- As soon as drive engages, remove radiator grille cover and turn air conditioning off to assist in engine cooling. After several minutes fan drive should disengage. This can be determined by reduction in fan speed and noise. If fan drive fails to function as described, it should be replaced.
- Fan drive should also be replaced if shaft seal is leaking fluid. If noise or roughness can be felt while turning by hand, replace drive. Frozen unit must be replaced. Blade tip rock of more than 1/4" front-to-rear indicates worn drive unit which should be replaced.
NOTE: Rotation speed will vary with engine temperature.