Adjustable Temp Electric Fans, Need help finding a sensor--page 2 Options

[computers4kids]

Currently I have dual electric fans, each on their own relay, that both come on around 180 degrees. I would like to reduce the fan noise from both fans coming on at once since my system stays cool easily and both fans tend to be overkill. I was thinking about having one fan come on around 180 degrees and the other come on if the temperature raises 10 degrees or so above. Fans 1 and 2 would also shut themselves off once each one dips 10 degrees below their set temps.

I see Jegs sells a kit that appears to do just this for around $150 that would control both fans. http://www.jegs.com/i/Derale/259/16789/10002/-1
Another possibility, would be to let Fan 1 continue to come on at 180 using the temp sender Renegade supplied, disconnecting the Fan 2. Jegs also sells the same adjustable unit for a single fan for $83. I would connect Fan 2 using the single controller for half the price. http://www.jegs.com/i/Derale/259/16779/10002/-1

What are your thoughts?

[76-914]

Yes, c1 & c2 are grounds which when are controlled (in my case) by the ECU. They provide the ground at their respective relays. #30 pin on #3 relay is getting it's "hot" from fan #2. The fans run together at hi or low speed. Or, they are off. They do not run independent of one another.