Hold your hand a few inches away from the vent so slight variations in temperature will be more noticeable. It may be a good idea to check the temperature of a few different vents. If the air flow feels suspiciously hot or weak, it could just be a bad vent.
A binding fan clutch will typically be accompanied with warm air flow from the A/C, since the fan isn’t turning the way it should be.
If the clutch does not engage when the AC is turned on when a voltage is present is a sign that the fan is damaged. Some fan clutches are designed with a built-in thermometer somewhere on the instrument panel. If your unit has one, keep an eye on the temperature so you’ll know about when the fan speed should begin ramping up. [4] X Research source If the fan still hasn’t kicked in by the time temperature reaches about 200 °F (93 °C), you can be sure that there’s a problem somewhere. You should be able to hear it from where you’re sitting inside the cabin of the vehicle. If the noise from the engine is too loud, try popping the hood to prevent the sound from being muffled.
You can also perform this test while the vehicle is parked and in neutral gear. Most fan clutches on newer vehicles are designed with a metal spring coil that reacts to changes in temperature and engages or disengages the fan accordingly. This means that the fan should power down at higher speeds because the rushing air is sufficient for cooling the engine. [6] X Research source
Never attempt to inspect or handle any of the mechanical components in the engine compartment while the engine is running.
When the engine starts to get too hot, the fan clutch takes the air flowing through the radiator, cools it down, and feeds it into the engine to cool it. Standard thermostatic fan clutches will only be present on cars and trucks with rear-wheel drive. Front-wheel drive vehicles are equipped with a completely different cooling system due to the way the engine is configured.
Check to make sure each of the bolts holding the fan clutch in place is secure and intact. Keep an eye out for any visible components that are bent, crooked, or missing.
In most cases, fan blades are designed to flex up to 1⁄2 inch (1. 3 cm). Any more than that could compromise the efficiency of the unit. [10] X Research source Give the water pump hose a quick jostle as well to see if the problem might lie there.
Inside the fan clutch, there is a small reservoir filled with a viscous silicone-based oil. The oil flows to and from the main chamber as engine heat fluctuates, engaging and disengaging the clutch. Traces of oil are perfectly normal, and won’t necessarily be an indication that your clutch is shot.
Ideally, the fan shouldn’t spin more than 1-1½ times. [14] X Research source For your own safety, you should never attempt to manually test your fan clutch while the vehicle is running.
It will cost somewhere between $150-300 to have a new fan clutch installed, on average. [17] X Research source Make sure your new fan clutch is the same type as the original. It’s possible to upgrade from a non-thermal clutch to a more efficient thermal model, but not the other way around.
