What is the easiest way to check a fan clutch? I can easily turn it by hand when the engine is off and hot. When running and I shut the engine down the fan stops without even making 1 complete revolution.

I am having some A/C issues and think I am not getting enough air flow thru my condenser. I am thinking the fan clutch could be bad.

Thanks, enjoy the Holiday
Frank D

 

when the car/truck is up to temp...and has been there for a bit..the fan should be going full tilt when hot...on the way to fla. 2 yrs ago the fan clutch gave out in my car...i could actually watch the fan spin and count the blades as the car was overheating..when cold some will spin fast with the engine for a few mins..but its not a big deal...zap!

 

Leaking fan clutches will usually sling oil all over the shroud and surrounding areas as well.

 

This one seems to be spinning very fast when hot.

I am having issues with the A/C blowing warm at idle, cold when the engine is revved up. I just replaced the evaporator, it was leaking, I now have a full weighed charge in the A/C system w/no leaks.

I ran the garden hose over the condenser when the van is idleing and the A/C blows cold. I am leaning toward a fan clutch being bad. It has never overheated.

Thanks
Frank D

 

This one seems to be spinning very fast when hot.



if thats happening its not the fan clutch...zap!

 

There is a way to see what the clutch is doing while the engine is running and warmed up.
If you can get a timing light to trigger on an engine with plug wires, off any cylinder, aim the light at the blades for about 5 minutes and watch the blade action.
On a COP engine i'm not sure this can be done with a normal timing lite.
If you see the blades appear to momentarly stop then reverse then repeat this action it is the clutch operating properly.
If not, it is faulty.
I also suspect that while moving down the road if cooling is ok you have A/C charge problems yet.
A locked up clutch will make the fan sound like an airplane prop at higher RPM.

 

While watching the fan have someone rev the engine. If the engine is warm you should be able to see the fan speed up with the motor if it is working. I have actually eased a piece of heater hose into the fan blades and stopped it when the clutch was defective...but I was younger and dumber then and I don't recommend this.

If you want to see if this is the problem with the a/c, set a strong electric fan in front of the condenser for a while and see if this helps.

 

Thanks for the replies,

The fan clutch looks like its doing its job, and I never overheated. Running the garden hose over the condenser gets the A/C to blow cold at an idle. Running at 1500 RPM fast idle, or driving, the A/C is perfect. I tested again for leaks, there are no leaks, compressor is quiet, and according to the gauges I have no blockages.

I hate to drop a full charge of Freon to replace an oriface tube, if the gauges are showing no blockages or leaks. This is driving me nuts.

Thanks
Frank D

 

I've a '97 Expy and a '99 F-150 and neither of them cool well when at idle. I suppose it depends on where you are located, as ambient temp and humidity make a big difference.

 

Hello all,
I have an F150 that over heats while I am driving at speeds over 35 MPH but it don't while it is idling. I have changed the thermostat because it kept rising into the red and then dropping like the thermostat was acting up. It is still doing the same thing except now it is only while the truck is moving.
I thought it might be the water pump but after a little more research I am thinking it may be the fan clutch.
I bought the pump and started taking it apart yesterday so now I cannot start it and check the fan.
Is there another way to check the fan while it isn't running?
Thanks in advance!
Heff

 

If it doesn't overheat when idling the fan clutch is fine. It's more likely an eroded water pump impeller.

 

Thank you!

 

Be sure to check the condenser and radiator for dirt/leaves/grass buildup cutting off airflow. Happens all the time on my fleet trucks.

 

What model year and mileage on your truck?
What part of the country do you drive this truck....state.
Right now most of the country is in a deep freeze so overheating while driving 35 MPH seems odd unless you are in a southern state.
This almost sounds like a head gasket issue to me especially the way the temp rises and falls so suddenly. A hot bubble of combustion gases can move through the cooling system triggering the coolant temp gauge to signal an overheat as it passes the temp sender. JMO.

 

You can try to reach in and grab it...

I read on one of these posts...someone's mechanic did it...

Seems to be a common problem affecting both cooling and A/C performance...