How does an automotive fan clutch work?
A fan clutch is a thermostatic engine cooling fan that can freewheel at low temperatures when cooling is not needed, allowing the engine to warm up faster, relieving unnecessary load on the engine. As temperatures increase, the clutch engages so that the fan is driven by engine power and moves air to cool the engine.
What activates the fan clutch?
Most fan clutches are filled with a silicone-based oil. The oil is held in an internal reservoir when the fan is disengaged. To engage the fan, internal valves open and allow the fluid to fill the working area of the clutch. This creates friction between the drive plate and the housing, causing the fan to spin.
What temperature should a fan clutch engage?
about 170°F
At what temperatures do fan clutches engage? Answer: Most fan clutches engage at about 170°F air temperature (about 180-190°F engine temperature). They reduce the temperature about 20°F before disengaging.
Should a fan clutch spin freely when cold?
A fan clutch is a thermostatic motor conditioning fan that may freewheel at low temp when cooling isn’t required, enabling the engine to heat up quicker and reducing engine load.
How does an air operated fan clutch work?
A Fan Clutch engages the fan and makes it turn when the valve opens; it pushes the PFD (Piston Friction Disc) against the friction material and also sends air pressure to overcome a spring. It disengages when the valve is closed, which allows the solenoid to exhaust air and let the spring return.
How can I tell if my fan clutch is working?
To confirm the diagnosis, start with this simple test: Spin the fan as hard as you can on an engine that has not been started that day. If the fan rotates more than five times, you can bet the clutch is bad. You should feel some resistance and the fan may spin up to three times, depending on the ambient temperature.
How do you test a clutch fan?
Does a clutch fan spin all the time?
Fan Clutch Types A small amount of resistance always keeps the fan spinning, but it’s basically free-wheeling until the fan clutch engages. When the fan clutch engages, it spins up greatly, increasing air flow through the radiator and over the engine.
How do you test a fan clutch?
How does a fan clutch fan clutch work?
How Fan Clutches Work. Your engine will overheat if not for the fan clutch. A fan clutch is attached to the front of an engine on rear wheel drive cars and trucks only. Bolted to the water pump between the water pump pulley and flange the clutch fan turns at engine speed and is driven by the serpentine belt.
What are the different types of water fan clutches?
The main types are non-thermal, thermal, and electronic — all of which use a silicone fluid to engage and disengage your fan. Non-thermal clutches operate solely based on the shaft speed of the water pump. At low and idling speeds, the clutch allows the fan blade to turn at almost a 1:1 ratio.
What is a heavy duty thermal fan clutch?
Heavy-Duty Thermal Fan Clutch: This fan style turns the fan at 70-90 percent of the shaft speed when engaged for increased cooling. When disengaged, it turns the fan at 25-35 percent. It’s used with deeper-pitch fans (2 1/2″ of pitch), and works well with higher operating rpm.
How do you know if your fan clutch is bad?
According to Hayden, here are some signs your fan clutch might need replaced: Fan spins excessively when engine is stopped (three or more times when hot engine is shut off). Poor A/C performance at idle or low vehicle speeds. Fan speed does not increase when engine is hot.