how to tell if fan clutch needs replaced on 2005 GMC Savana 2500

air condition is not as cool as it was last year

Asked by for the 2005 GMC Savana 2500
The fan clutch on a truck driven of the engine either fails and causes the engine to run hot (the gel in the hub leaks out and no longer is able to expand and "lock up" to cool the engine the other way it fails is it "lock up" and fails to release causing a load noise all the time. Its function does not affect a/c output.Poor a/c operation is normally low refrigerant charge.