What could cause my driver's side(primary) fan to go ON right away during start-up on a cold engine?
This seems to happen on warm weather only (75-95 degree days).
On cooler days (50-70 degrees it doesn't happen.
Also when the fan does come on right away the engine idles very low and sometimes stalls. At WOT it runs great.
91 Z28 LB9 TPI

 

i tried to answer some of the question in ur other thread.

when the fan comes on and the car is on what is the voltage meter read?

might have a problem with the tps and or iac.

my car has a very low low speed idle problem and stalls sometimes, but runs great wot.

i think my throttle body needs a good cleaning.

 

stalling and the driver's side fan coming on right away, indicates a fault. i would suggest replacing the cts first. a bad cts would give the ecm skewed readings and can very well be telling the ecm the engine is @ 260* when it's not. a faulty "stuck on" fan relay could also be the culprit (fan problem only).

both of these are cheap and easy repairs.

 

OK, I've fixed the stalling problem thanks to Thirdgen.
Found that my IAC was seized in the closed position. Loosened and cleaned it up along with my Throttle body.
My fan still comes on when the engine is cold though.
At least it is driveable now. I'm happy.

 

has this been doing this ever since you owned the car or did it just start? Does it look like there has been some wiring added tot he fan at all? Look under the steering column and find the fuse panel. Look for any wires plugged into the IGN terminals.