JoeNooch

Hello, I'm doing some work on a 1991 Z28 305 TPI. None of the cooling fans work when the car gets hot. Long story short, I have done multiple tests and replaced several parts with no luck. Everything is indeed circuited correctly, as grounding tests turn the fans on. I think I'm just going to pop in a new temperature switch, tie that into the primary fan, bypass the computer, and have that control when the fans go on (i'll also set up a toggle to manually turn on the fans). In order to do this I obviously have to put in a temperature switch that closes at a lower temp, opposed to the one currently in there that closes at 240 degrees F. My question is, what is a good temperature for a temperature switch to close and turn on the fans for my type of car and engine? I know that the primary is "supposed" to come on between 200 and 220, and I've read some threads of people putting in switches that turn on at 195. is 195 too low for my car? in addition, i just bought (but haven't yet installed) an OEM 195 degree thermostat. I have read of people buying 180 degree thermostats. can my car operate with a 180 degree thermo? will that help cooling? In other words, what temperatures should I have the car run at? will having the fans come on at a lower temp mess up the car/performance? Any help is appreciated! Thanks!

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Zralou

You need a thermostat that will open earlier than the fan turn on temperature. Having them both at 195* will cause problems with cooling.

Sara Lou

Reid Fleming

My signature shows 1991 advice for fan troubleshooting.

Buy the 200/185 fan switch. Works great in summer and winter. Doesn't run all the time, wearing out fan motors like the 177/165 fan switch does. It won't run in the summer unless you need it to. Probably won't run at all in the winter time.

195° thermostat? I wouldn't. 180° seems to work rather well for me. And I live in hot muggy Texas. My car really likes running at 180°. I used to drive my car in Canada with the 180 and even the 160. I preferred the 180 in both climates. Only benefit to 195 is a minor increase in fuel economy (about 0.5 mpg)

I prefer to not manually tie both fans to the same turn on point. The peak voltage requirement that that causes can be hard on electrical. Just get a different chip that turns your first fan (driver side) on earlier.

My cooling setup is rather simple, but effective. 180 stat, chip turns 1st fan on earlier (190/185), fan switch (200/185) for the 2nd fan. Keep the radiator clean and make sure the air dam is functional.

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Cooling fan diagnosis