Why control dual cooling fans seperately?

[BonzoHansen]

I love my DCC controller - using 4th gen fans, damn thing is great. I never hear my fans running and one of them has a growl at full voltage. It did when I put them in 4 years ago and I expected to have to change it. Not yet. If I did not have that I'd have run 3 relays and run them both at 6v at a lower temp and both at 12 volts if it got warmer or AC came on. That is how GM wired the later 4th gens. I’m no engineer, so I figure if GM decided they needed that extra ‘complication’ there must be a reason. Down side is you need 2 fan switches to do that w/o a controller. There is a thread at nastyZ about a dual temp BMW switch that is perfect for it.



I had the exact same issue in my Z with the temps. It would run 150* or less on the highway and perfect 185* at idle/local. Stat was hanging open, and it was a relatively new (~2 years) Robert Shaw type. new stat fixed the issue. Same issue with my DD olds just this fall. New stat problem solved. Just throwing that out there.