Universal Thermal Radiator Fan Switch & Adapter Kit

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0.21 KGS

The Stoney Racing Radiator Fan Thermal Switch & Adapter Kit allows you to thermally control any aftermarket universal radiator fan. Perfect for kit cars or older vehicles that don't use electric fans as standard.

The switch actives when the sensor reaches the "on" temperature and turns off when it drops back below the "off" temperature. With seven different temperature ranges available and adapter sizes to fit radiator hose I.D.'s from 26mm up to 40mm our kits provide an easy fan switch fitting solution for almost any vehicle.

The kit includes a pair of good quality fully stainless steel clamps, with no perforations in the band and featuring a rolled edge, suitable for all rubber and silicone hoses.

Ideal for use with our range of high powered fans featuring sizes from 7" to 16" and motors from 120W to 220W.

What Switch Temperature Do I Need?

This varies from vehicle to vehicle and colder is not necessarily better as the ideal operating temperature range for an engine may be higher than our "coldest" switches would allow it to reach.

A good rule of thumb is that the on temperature of the switch should be around 12°C to 18°C higher than the vehicles rated thermostat opening temperature i.e. the temp the thermostat begins to open at.

So for example if your thermostat starts opening at 74°C you want an "on" temp of 86°C to 92°C so you would use the 90°C on switch. If your thermostat opens at 82°C you want an "on" temp of 94°C to 100°C so you would use the 95°C on switch.

Thermal switches available:

  • 80°C on / 72°C off (± 3°C)
  • 85°C on / 77°C off (± 3°C)
  • 90°C on / 80°C off (± 3°C)
  • 95°C on / 85°C off (± 3°C)
  • 100°C on / 90°C off (± 3°C)
  • 105°C on / 95°C off (± 3°C)
  • 110°C on / 100°C off (± 3°C)

What Size Adapter Do I Need?

To determine what size adapter you need simply measure the inner diameter of your top radiator hose and choose the matching size from our store. The adapter will fit hoses 1mm smaller than it so a 30mm adapter can be used for hoses 29mm-30mm I.D. for example.

Some top radiator hoses are larger at one end than the main body of the hose so if this is the case for your vehicle take care to measure the end that is the same diameter as the part you will cut to fit the adapter.

Available in adapter sizes 26mm, 28mm, 30mm, 32mm, 34mm, 36mm, 38mm and 40mm O.D.


Important: The switch must be installed in the low current side of a relay (i.e. one of the wires to pins 85/86 on a standard 4 or 5pin relay) and the adapter must be fitted in the top radiator hose for the switch to function properly.

To fit simply cut your top radiator hose at a straight section into two pieces using a stanley knife, using a hose clamp lightly tightened around the hose as a cutting guide. Remove approx 30mm length of hose from one of the cut halves which the adapter will replace. Rejoin the two sections with our adapter and the clamps provided and refit the hose.

For wiring we recommend running the fan directly from the battery via a relay and inline fuse, with the relay activated from a 12v + switched ignition source. You can also use a constant 12v source to activate the relay instead and this will allow the fans to continue running after the car is turned off until the coolant has reached the "off" temperature of the switch, as many modern cars do to aid with engine cooling after running.

The switch should be wired into the ground wire for the low current side of the relay. The switch is only suitable for up to around 1A of current draw, and most fans draw at least 5A of current, so wiring the switch directly inline with a fan will blow the switch.

11 Reviews Hide Reviews Show Reviews

  • 5

    Posted by [email protected] on 22nd Jul 2022

    It works perfectly for a reasonable price, I would buy it again.

  • 5
    universal fan switch

    Posted by jay on 27th Jun 2022

    this i fitted onto a pre 98 mercedes v6 2.4 as the engine always got too hot during stationary traffic even with a good rad good water pump and lower opening thermoststat fitted in 1 hr and works far better than the original thermo switch the car nows sits in stationary traffic without overheating and gauge stays in normal range good fitting works well simple to fit even for a non mechanic like myself

  • 5
    fan switch adapter

    Posted by trevor fox on 26th May 2022

    i managed to fit this in the very limited space on a TR3A using some 38mm hump hose at one end to allow for movement. far better than using capillary switches or fitting to the bottom hose. a great piece of kit.

  • 5
    Worked great for MGB GT

    Posted by Ted Smith on 21st Jan 2022

    Bought this to replace some customisation my dad had made to the top hose of MGB GT. great help from the company pre purchase and it worked great. No leaks. No extra parts needed.

  • 5
    Hose adaptor and thermal switch

    Posted by John on 5th Jul 2021

    Tbh, I was surprised by the quality of the component for the price. Excellent!