View single post by Mark Rosenbaum
 Posted: 08-14-2005 05:49 pm
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Mark Rosenbaum

Joined: 03-12-2005
Location: Kingman, Arizona USA
Posts: 532
Yes, antifreeze added to water will raise the boiling point, the increase depending on the amount of antifreeze present.

239^F is pretty close to the boiling point of a 50/50 antifreeze/water mix, so the temp switch you refer to is probably intended to disable the air conditioner when the engine gets too hot.  If your Saab were carbureted rather than fuel injected, I'd want the disable temperature about 20^F lower.

For switching an electric fan that's intended to cool the radiator, you usually want a switch that will turn the fan off about 5^F-10^F above the nominal operating point of the thermostat, and turn the fan on some 10^F above that.  Only the turn-off temperature is of any real importance, so there should be a wide assortment of suitable switches.  If you can find a short length of brass or copper pipe of the right diameter, it should be easy to make an in-line mount for almost any switch design.

There are several ways of arranging a manual switch, each with advantages and drawbacks.  My choice would be to use a good reliable solid-state switch and fan controller.  Properly done, the least reliable part would then be the fan itself.