Just ran my car around the block, testing to see when my fans come on and shut off with the miata thermo switch. I have a cyberdene digital gauge with the sender tapped into the filler neck right in front of the thermostat. My gauge seems to run about 5 degrees high. Drove it shortly, parked it with it running. Gauge showed 212, fans came on, then it steadily climbed to 225, the fans shut off, then it fell to 208, then started warming back up to 212 where the fans came on again, the it started steadily rising back to 220 before I shut it down. What the hell??



thanks

 

how about you just wire up a switch so you can turn em on or get a PFC and you can program the temp you want them to come on at

 

I have the fan mod switch set up where I can turn them on and let them run while city driving, but that's not the point, the temp shouldn't rise if the fans turn on.

 

Yousure the voltage from the fans is not screwing with your readings?

 

what do you mean the voltage from the fans screwing with the readings. I don't think I have it setup any differently than most. How would the voltage affect the gauge?

 

are both fans going on high speed ?

 

can't really tell

 

You are not getting an accurate reading from your temp sensor. You have it mounted in front of the thermostat which is opening and closing. The thermoswitch is mounted in back of the thermostat so it is turning the fans on and off correctly, it is your gauge reading that is incorrect.

 

I have seen them rise before they lower with the fans on. Thermostat might be the problem, its always open since its set low. So it takes longer to get the water temps down, so by the time the cooler water gets there, the temps will continue to rise.



Makes sense right?



Anyway, what gauge are you using?



I had this happen on my car, but I was running off C not F and sometimes it rises about 3-4C degrees before it starts to lower since I also have a BILLION low temp Thermo.

 

The thermostat should be opening at 185F, and really shouldn't be closing at all right, if the normal driving temps stay above 185F like they usually do, then it should stay open until the car cools, I know it opens at varying rates but still it should be open at all temps past 185F.