My daul electic fan setup comes on at 225 deg. Can I replace something to make it come on at 200 deg. The car is a 1989 Firebird Formula 350 with the L98 motor.

 

You have a few options to consider. Your two fans should come on at different temperatures and depending on if the air conditioning is engaged. The primary fan on the drivers side is controlled by the computer and comes on first, the secondary fan on the passengers side is controlled by a temperature sensitive switch bolted into the passengers side head. You can buy replacement switches by Jet and Hypertech to engage the secondary switch at a cooler temperature. One of these companies also sells a adapter to manually engage the secondary fan inside the car or your can fabricate one yourself. Then you can buy off the shelf PROMs that will engage your primary fan at a cooler temperature; however, I would not waste your money on these. Finally, you can have a custom PROM burnt to engage the primary fan at a different temperature and I have heard it is possible to design the PROM to control the secondary fan, but don't quote me on that. You will also want to consider a cooler (160 or 180 degree) thermostat with these options.

 

I have put a 180deg stat in already. One thing, both fans come on at the same time. The A/C has been coverted to the new stuff. I've read on here that the new stuff in the A/C is installed at a higher pressure and the EMC may thing the A/C is on. What can I do?

 

It is peculiar that both fans come on at the same time as they are controlled by different systems and set to engage at different temperatures. I cannot say how this has occurred and how a modified air conditioning system has affected the operation of the fans. Maybe the switch to control the secondary fan is broken and just happens to engage when the primary fan turns on. Possibly the car has a PROM in it or the altered air conditioning system happens to engage the primary fan at the same temperature setting as the secondary fan, but I doubt it. You may still be able to install a switch for the secondary fan, which set the temperature threshold lower than the primary fan. Thus the secondary fan comes on before the primary fan. Alternatively, you can obtain a custom burnt PROM to change how the fan engages; however, this would not be a preferred option. You custom burn a PROM to do a lot more than just adjust fan on/off settings. Finally, you can rig up a manual override for the secondary fan.