low cooling fan kicks on at 216-217 degrees and the high cooling fan kicks on at 225-226 degrees. I know this from changing my thermo recently and had a computer hooked to the car to watch the temp. after i changed my thermo., i would have the temp gauge go up on me from time to time because of air bubbles left in the system, they will work themselves out or you can do it while the car is parked by just reving the car up from the throtle, i found that if you watch your overflow tank while reving the car up, you will start to see some bubbles come up from the bottom of the tank. have someone sit in your car and watch the gauge so they can shut it off if it gets into the red. also remember, the system is very big so there can be more bubbles in the system than you think, i sat for 2 hours reving the car periodically for about a min or so each time to get the bubbles out. also, your car should run at about 198-204 range. also, what is cosing you $300 to replace, the gauge or the WP?