These toyota clutch fans are designed to, "fail to lock". Another words, they stay in the locked up state when they fail. Thats why they sound so loud all the time, when they go bad.
Stranger things have happened though.
If the clutch is working properly, the fan will disengage after the first few seconds (and quiet down), and then (time depends on the ambient temp, etc.) after a while, when the small amount of air that is coming past your restriction gets hot enough, the fan clutch should sense the heat and engage again, making the same amount of noise (and pushing the same amount of air) as it did immediately after start up.
So even if they fail, they stay locked?..which means it shouldnt be the cause of overheating as it draws air all the time?
I think the fan clutch is working propery. It is louder, spins faster and draws more air on first 15 seconds and then quiets down at cold start. I took it for a drive and parked it with the engine running. I placed a cardboard infront of the radiator for about 10 min. It didnt engage. I even blasted the AC on for a few minutes. It is about 80 degrees outside. How long will it take for the clutch to engage?
Few things I forgot to mention: the water temp gauge stays at halfway even if its already over heating. It starts at L and goes up halfway as the engine warms up. Although, it creeps 3/4 up when I drove it on the highway when it was 100+ degrees.
Oil pressure gauge hovers at 1/8way at idle and goes up to 1/3-1/2way up as rpm goes up.
