Fan & Fan Clutch Issues

[Champ193pro]

I just had my air compressor go out this last weekend. After troubleshooting what happened I discovered that my fan clutch may have gone out. From what I remember about them, they should turn at a fairly rapid speed under normal operationg temps. Then kick in when there is a hi temp condidtion.

On my F350 2004 6.0, when I start the motor it turns at a rapid rate then dies off to almost a crawl.

What is the best method to test to determine whether it is bad or not?

Also, has anyone removed the stock fan and clutch and installed aftermarket electric hi volume fans?

Thanks

[Misael]

Subscribed. Would like to know more about how they operate! I don't really hear mine much, under normal operating temp doesn't really turn that fast either