Two responses:
1] Borg Warner TFS545 or a crossover, will come on before the OEM sensor does. (std354 said this)
2] The thread for the switch is 16m x 1.5. From a 1988 Chevy Sprint, part number Beck Arnley 201-1367.
Closes @ 185 Deg. F; Opens @ 194 Deg. F
(from in this thread)
https://www.vmaxforum.net/threads/02-vmax-radiator-fan-issue.25524/ (dingy said this)
3] from firefly:
https://www.vmaxforum.net/threads/thermo-switches-to-solve-overheating.112/
1- BORG-WARNER TFS-545,
2-WELLS-SW537 ,3-Nissan sentra 1988
4] from richwrench:
FWIW - I'm running a Borg Warner fan switch # TFS545 & a Stant thermostat # 13758 ( 180 degree ) here in west central FL with no probs - gauge never rises above the dot - no manual over-ride switch for the fan , but I'm not pushing it as hard as others may be. Parts were in stock at Advance Auto.
5] Sean Morley once contributed this:
The easiest way to to the manual switch is simply mount your switch in the desired location. Run one wire from one side of the switch to one side of the sending unit (I use a male spade connector and push it in to the back side of the connector so no cutting involved) and then the other side of the switch to the other side of the sender. The sender for the fan is the two wire switch in coolant chamber under the right scoop.
You can also splice each wire in with the existing wires or even use the clamp on type of connectors. I do it this way so there is no power wires to run, if you shut the bike off the fan shuts off (it's easy to forget about it being on), if a wire falls out nothing gets shorted, the wires are very short in length if you put the switch in the screen in front of the scoop or into the same cover that the ignition housing passes through, and the system still operates like stock unless you override it with the fan.
Super easy to do. Takes 2 wires about 1' each (or less) and one switch.
Sean Morley
6] an addendum to the above post by Sean Morley:
when you remove the right scoop. The sender is the larger screwed in unit with 2 contacts. Run one wire to one side and one wire to the other from your 2 pole non-lighted switch (or ignore the third terminal for those types of switches). It's that easy. I usually just use male spade connectors and push them into the backside of the connector right on top of the existing plug (with it plugged in). In this manner if the connector falls out there isn't anything to short out and if you forget to turn off the switch the fan turns off with the key.
7] maleko89 said:
Both the fan switch and temperature sender are in the coolant manifold. Fan switch is the bigger of the two.
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And always useful info on this in RaWarrior's thread:
https://www.vmaxforum.net/threads/new-vmax-owner-faqs-new-members-please-read.21240/