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K-Roll931 · Joined: 08 Jul 2017 Posts: 76 Location: Southfield, MI

I'm positive the thermofan switch on my 931 is on it's way out and because I can't remember what temp thermostat I originally purchased (IF I ever did, I can't find any record of it...) I'd like to change out both. Problem for me is I've no idea which t-stat/fan switch combo is best for me??

I'm used to my car running at the first tick most of the time (city driving, sitting in traffic, highway, and it's almost never gone past the second/middle tick without the cooling fans coming on. I will say that when it comes to cooler and cold fall weather, it sits between the first tick and first/white square and that can't be ideal. There's a plethora of t-stats and switches to choose from, and I'd like to know what combo would be best suited for consistent and cool running but not too cool nor fans running all the time? As in, it'll never go past the second middle tick?

T-Stats: 71C/160F, 82C/180F

Switches: 75-70C, 82-77C, 92-87C

I'm thinking the 82C T-Stat with an 92C fan switch would be the right choice.
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'80 931 M471 - Dolomite Gray -> Monaco Blue

Raize · Joined: 18 Sep 2013 Posts: 447 Location: Scotland

I don't know about Turbos, but my N/A has the 82C thermostat and like your turbo it sits between the white zone and the first tick. The fan switch I'm not sure what it is, but it usually comes on just before the red zone.

I'm considering trying the 87C thermostat that's available.

They're very cheap and easy to change anyway.

Paul · Posted: Mon Aug 10, 2020 11:55 pm Post subject:

Over the decades, I've tried several combinations but have decided that the stock setup, when working properly, is my preference for year round driving in northern climates.
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White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.