Maybe one of you guys/gals can help with this one.
My 88 Formula race car with a warmed over 2.8 is running both a low temp thermostat and fan switch.
I have not had any luck with the switch. 4 switches in 6 years. last two were Rodney's.
Have an over ride switch to turn the fan on if needed due to the block switch failing on many occasions.
Any thoughts? I just ordered another one from Rodney.

FYI, i used paste sealant not Teflon tape and the circuit does work when grounded to the switch body

[This message has been edited by mcguiver3 (edited 03-28-2024).]

Which of the two low temp fan switches that Rodney sells have you used? I've had his 200°-210° fan switch in two of my Fieros for many years with no issues.

i read that the fan is controlled by the computer on the 87-88.i was going to get a lower temp sender.

quote Originally posted by richard in nc: i read that the fan is controlled by the computer on the 87-88.

Yes and no.

2.5 I4 - yes.
2.8 V6 - no.

My thought would be either it's not grounded well enough or the wire/connector bad a break in it somewhere, if you've tried 4 switches, the problem isn't the switch, so my guess is the wire has a break that is causing an intermittent connection, working enough to make you think it is working, but not working enough that it is annoying. Also, with a cooling system that is working properly, the fan should never come on when driving over 10-20. It should only come on after idling for awhile, even with the lower temp fan switch. Also the factory temp gauge is famously unreliable, it can read substantially higher then it really is, my fan didn't turn on until the needle was 1/4" past the red, I rewired it to not peg upon startup, recentered the needle, and now with the Rodney 98°c fan switch, it turns on at 100°c on the gauge, just like it's supposed to.

Hey mcguiver3,

When you said "no luck" with the fan switches and the circuit does work when grounded:

Did you TEST these 'bad' temperature switches in a pan of hot water and verify with an accurate thermometer and an ohmmeter that the switch didn't close the conducting path?

The temperature switch should close at the "high" degrees and open as the temperature falls back to the "low" degrees.

To me, if you verified these failing switches as stated above; the failure is 'quality' and not your Fiero assuming the fan circuit is 'stock'.........

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Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles

[This message has been edited by Vintage-Nut (edited 03-29-2024).]

yes, multiple fails can be iffy wiring...
Or fan relay rewired/bad & now the switch seeing full amps for the motor & burn out. + Manual switch can fry for same reason.
They are not made to handle motor eating ~ 11A or to Handle inrush or shut off power the motor pulls @ startup or coil crash generating Negative 100 or more Volts. Amp & Volt rating for switches & relays printed on them are for AC Resistive Loads such as Standard Light Bulbs. If say DCV then much lower volts & for Resistive Loads.

Fan should Not turn On most times when car is moving, more so @ highway speeds but popular bs says need the fan all the time.
(That ignoring Fiero AC "head" that forces the fan On no matter what if have pushed AC, AC Max buttons...)
Fan is On a lot often means coolant system has problems... crush pipe(s), plugged "tubes" in rad &or heater, dirt on rad or AC coil in front of the rad, etc.
But many just believe the hype & buy lower rad switch etc. & still have problems because never fix the real problem(s).

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave