THERMATIC® FAN SWITCH (Mechanical) (Part #0401)

The Mechanical Thermatic® Fan Switch can be used with our Thermatic®  Electric Fans & EWPs®. It senses the coolant temperature after it passes through the engine block prior to entering the radiator and is adjustable from 40° to 100°C (104° to 212°F). The Thermal Switch is mounted near the radiator and the stainless steel probe fitted inside the radiator hose. The Thermal Switch & relay kit enables a fan to operate both thermally and also when the air conditioning is running.

Sensor Wire Length: 110cm





Thermal Switch & Accessories


2 x screws to connect bracket to car
2 x small screws to connect switch to bracket
1 x bracket
2 x blue butt connectors
2 x spade terminals
1 x blue wire (switch to ignition)


Rubber Seal Suits 1mm Capillary


Thermal Switch Knob


Red Wire Joiner






Temperature Range

40° to 100°C (104° to 212°F)

Lead Length


Sensor Probe Size

Suites 6mm Olive



The switch requires relay & wiring harness to run your fan.

*Not included in kit

For Single Fan:

  • Part #1000 (12 Volt)
  • Part #1001 (24 Volt)

For Dual Fan:

  • Part #1002 (12 Volt)
  • Part #1003 (24 Volt)



Should you not want to squeeze the probe of the Mechanical Thermatic® Switch between the radiator inlet and radiator hose, or the radiator fins, we recommend you look at part number 0409 or 0400 (Sold Separately)


The #0409 is a simple, economical Adaptor Kit allows easy fitting directly into the top radiator hose. Just fit the probe into the compression fitting, remove about 17mm (2/3”) of radiator hose, fit the adaptor between each hose and secure the hose clamps. The kit comes complete, as shown, for a watertight and effective probe installation. Extra rubber sleeves are supplied to enable fitment to radiator hose sizes from 32mm to 40mm (1¼” to 1½”) diameter. Suits all temperature sensors with either a 5mm (3/16”) or a 6mm (1/4” outside diameter and temperature gauge senders with 6mm (1/4”) NPT thread. 

Note: This is an accessory for use with #0401, #0404, #0444 and
#0500 Thermatic® Electric Switches.


Should you need to account for Air Conditioning, we recommend the Mechanical Thermatic® Switch(12V & 24V) plus Relay for Air Conditioning, Part #0404

Davies, Craig Range of Thermatic® Electric Fan Switches

  • Part #0444 senses air temperature near the top radiator hose as it passes through the radiator or senses coolant temperature (with #0409) for single or twin fan operation.
  • Part #0500 The Digital Gauge Thermatic Fan/EWP Switch offers the state-of-the-art digital features of that the value-packed #0444 Thermatic® Switch offers and more!
  • Part #0401 senses the coolant temperature after it passes through the engine block prior to entering the radiator.
  • Part #0400 is a combination of the unit #0401 (opposite) and the #0409 Hose Adaptor (opposite), offering probe placement in the top radiator hose.
  • Part #0404 Mechanical Thermatic® Fan Switch & Relay (12V & 24V) for Air Conditioning can be used with our Thermatic Fans & EWP's.


*Note: if using this switch for use with our EWP's, it will not vary the speed of the pump in response to engine temperature but rather turn the pump on and off at your set temperature. For EWP control, we would recommend the Digital Controller part number 8002 which can manage both the EWP and your Thermatic Fans.

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