01 S10 and 02 Envoy-Clutch fan help.

Yesterday the cooling fan on our 02 Envoy started to make a "jet engine" noise. My S10 will make this noise but for only a minute or so. I heard that this is normal for the clutch fan setup. The Envoys fan always worked the same way until yesterday. When you would give it some gas the noise sounds like a jet engine. What's the best way to troubleshoot this? I just got done driving the S-10 to warm it up. I turned it off and checked how easy it was to spin the fan by hand. You could turn the fan very easy. Did the samething with the Envoy and it was about the same. I have double checked and the Envoy's noise is coming from the fan. Today it's rather warm(72 degrees)and when I started the S-10 you could not here the fan noise but on the Envoy you could. Always dealt with electric cooling fans in the past. I know very little about the fan clutch setup. Where should I go from here? Many thanks for your advice.

Sounds ok to me. The fan clutch is temperature activated and temperature changes affect how they act when first started. They've been quirky that way a long time. My '70 GMC original fan still roared when first started while I drove it in '98.

Only when it roars when you drive it should you replace it.

Yes something is wrong with it. It "roars" all the time. Have driven many times in the past 2 days to see if it would stop. No luck. The noise is coming from the fan. So I would assume the clutch fan needs to be replaced. What size wrench does it take to loosen it? My S-10 looks like its got the same setup and both are the same size? I would think I would need a very long wrench. Just need to know what(mm?)size of wrench to get. The job looks pretty straight forward. I would like to do this myself. Thanks for the info!

I don't know the size for sure, but take some wrenches out there and check.