Have a 2004 s10 blazer. 4 door 4wd. When a/c is turned on, get a turbine sounding noise from transmission. All gears still there, but shifts at lower rpm. Turn a/c off and within a 100 yards tranny goes back to normal. Installed new alternator and new battery. Dropped tranny pan and installed new filter. No signs of clutch material or metal frags. Also installed new boost valve in pump. Any ideas?

 

Turns out to be the clutch fan. New clutch fan installed several weeks ago and with recent heat and use of a/c it goes into thermal lock and just kills the HP of engine. Guess it is time to look into a suitable electric fan as a replacement.

 

You should be good with a regular heavy duty fan clutch

 

Thanks SPITTY. Any make you recommend

 

Hayden from Advanced auto parts is working for me!!!