Coolant temp sensor thread size??

[Xanatos]

Not to hijack the thread, but I though this might be relevant rather than starting a whole new one.

Is the "radiator cooling fan sensor switch" a simple off/on at a specific temperature, or is it variable? If so, would anyone know what the temperature trip point might be? Reason I ask is I'd like to hook into this circuit as a trip for the relay controlling my electric fan setup. I already have a threaded sensor in the radiator, but I'd like to have a backup on the t-stat housing as I feel the temperature reading there might be more indicative of needing to turn the fan on as opposed to just the one in the radiator. I've tried hooking into the one for the AC Coolant sensor switch as I assumed it functioned the same as my aftermarket one that I installed in the radiator (looks very similar). It is possible that it might not be working just because the sensor could be bad too. Otherwise, I'm thinking about yanking one of those t-stat sensors out and replacing it with an aftermarket one. Where can one find the 14mm x 1.5 to NPT adapters?

Thanks in advance guys and gals.