Alternative to Miata thermoswitch
 

Hey all -

Just got a new (to me) copy of RX-7 Magazine and I'm flippin' through trying to decipher what they're talking about without being able to read Japanese :). They show a pic of 2 coolant thermoswitches, and in the text you can see "FC" and "FD".

I put it together - they're talking about using the '89-91 FC fan thermoswitch. I believe it's actually IDENTICAL to the FD switch (uses the same electrical connector and everything) but has the same temp range as the Miata switch. Dug out my '89-91 shop manual - the '89-91 FC thermoswitch turns on at 97 deg. C (207F) and switches off at 90 deg. C (194F).

It's the same part, turbo and non-turbo, BTW. The switch is for the small electric fan in front of the radiator on the FC.

From what I've seen, the Miata switch comes on at the same point, but this may switch off at a lower temp. Not sure.

Thoughts?

Dale

If all that's true it sounds like the perfect plug and play replacement. I'm just curious why nobody noticed before?

I'm curious why Mazda didn't use it instead of the one the comes on the car.

It's a good question why they didn't use it. I think they were trying to run the system hotter for better fuel economy or something.

BTW, I'm already hoarding FC parts that work on the FD :). I have a feeling I'll be finding a LOT of crossover, since I know FC's so well. Found out this weekend when working on my buddy's FD that the metal clip that holds the door lock into the door handle is the same. His was broken from an attempt to steal the car - grabbed one off the parts car and he was good to go.

Dale

Thermoswitch
 

Do you have a part number for the 89-91 FC thermoswitch?

Since 2 people have already PM'd me on the topic, I figured I better jump in here :).

I still haven't tried it, since I still don't have an FD to try it on :). I was hoping to get the loan done this week and start shopping, but Hurricane Ivan is shutting everything down - I'm in Pensacola, right in the path. Wish me luck there! :)

Anyhow, I see NO reason why this sucker wouldn't bolt in, plug in, and work as advertised. Seeing pics in the RX-7 mag right next to each other, they look identical.

I don't have a part number - just call up Malloy Mazda and get with Ray Crowe, I'm sure he could find it in a jiffy and get it on the way to you.

Dale

So does this mod work ? I'm ready to do this or the Miata mod.

Thanks,
:-) neil

Ditto...this would be a SWEET plug 'n play fix. Nice catch! :bigthumb:

Stock switch keeps fans on for about 10F drop in temp, per fsm. I tested a miata switch, and it stayed on for about a 5F drop, as I recall. I think napa type miata switches were posted as 10F drops.

Any of the above is better than the 221F ecu limit for slow speed (medium speed switched at 226F) for emissions testing.

Ditto. I'm thinking of doing this as well.

paging Kevin Landers...

so did anyone ever get this tried out on their fd's?? i am deciding on which cooling fan mod to do, this seems the easiest

Still would like to know if the FC switch worked. Just bought a Miata one and ill return it if i have to for the FC thermoswitch.

Interesting that the thread was bumped today :). I've got the FC thermoswitch in hand, and it's going on the car today. I'll be finding out soon enough!

Dale

HAHA sweet. I just bought the miata switch yesturday and was doing a search on install. If this FC one is a plug and play ill return it for the FC and make my job easyer......let us know
cheers

With a stock ECU, I say great Miata switch it now, but if you have a Power FC, AEM, Haltech, ETc... just lower the temp when all fans come on in the map, no switch/sensor required....

I'm quite interested in the result!! I am about to purchase a miata one... If this works I will definitely be getting the FC one instead.

Mitch

See this post -

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/its-official-do-not-buy-miata-thermoswitch-until-you-read-397156/

It's official - the FC switch works great!

Dale