I've asked a number of people about this and the only answers i got were to replace the ECM, which i'm still not convinced of. On 75 degree + days the fan wont turn on without the airconditioning. I've seen it up to 250-260 before i noticed it. I know that with the whole automatic overdrive thing, the fan comes on with ac, but why wont it come on otherwise??? Thanks a lot.

 

The fan switch needs to be replaced. It's on the passenger side head between the #6 and #8 spark plugs. You can order one from Jeg's or Summit for around $40.

 

you should have two fans, they both come on at different times and temps.

the drivers side should come on first and at 227 or close to that.
anyway that runs off a temp sensor in the front of the engine and that sends the temp at which the ecm will ground the relay and turn on the fan.

the passengers side works like GKK said, by the fan switch, or the a/c pressure switch, your pressure switch must work since you said the fan comes on. the stock fan switch is setup to like 238 degrees or close to that and that will ground the relay and turn that fan on.

this is what i did,

180 stat and wired in a switch to manully override the passengers side fan since i did a/c delete and i didnt feel like changing the stock fan switch again.