T-stat & thermo fan switch temp pairings?

Question

The couple of cars I've owned have been set up like the following example:

89C/192F t-stat | 87C/189F - 92C/192F thermo fan switch (to turn on the cooling fans)

Is the proper setup to have the thermo fan switch temp range straddle the t-stat temp (and is this a typical stock pairing, distinct from the usual running cooler/hotter options/discussions)?

Or would a 89C/192F - 94C/201F thermo fan switch be preferable in the above example? Obviously the temps and fan cycle times would be different - just looking for a bit of discussion on the topic of pairing

Thank you

Stephen Bigelow · Accepted Answer

The stat controls the temp of the engine, and the fan switch controls the temp of the rad.

You'll probably want the rad cooler than the engine.

Your second example, sitting in traffic: Engine gets to 192, stat wide open, sending bloody hot coolant to rad.....which might just send it back at the same temp!

Not ideal.

Robert Hancock · Answer

I'm assuming 192 is the on temp and 87 is the off temp? That sounds wrongfor a 192 thermostat, then - the fan might never turn off. Usually thefan-on temp is a fair bit higher than the thermostat regulating temperature,for fuel economy and noise reduction reasons I believe..

Stephen Bigelow · Answer

Ahh-ha!Well, that's why I(a) don't design cooling system parameters(b) replace cooling system controls with factory parts.Cheers.

T-stat & thermo fan switch temp pairings?

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