Thermatic Fans

Thermatic Fans FAQs


Question No. 1
What size Electric Fan(s) do need?
The size of correct application for electric fans vary greatly with each type of vehicle. Firstly consult your Davies, Craig selection guide. If the vehicle is not listed then measure the available radiator core area and space in the engine compartment between the radiator and the water pump or in the front of the air conditioning condenser. Then consult your Davies, Craig catalogue for the recommended fan sizes. Generally the larger the engine the larger the fan required. Upgrade to a larger size if yo have a turbo or tow.It is important to follow these recommendations to ensure that you will get adequate cooling even under severe driving situations. 

Question No. 2
What is the difference between a Thermatic Fan Kit and Short?
Davies Craig Thermatic Fans are available in two packaging options:

  1. KIT - includes: Fan Assembly, Wiring Loom, Relay, Mounting Hardware, Comprehensive DYI Fitting Instruction Sheet for automotive application
  2. SHORT - includes: Fan Assembly (motor, fan blade, shroud), Installation Instructions

*Davies Craig offer Kit and Short Thermatic Fans in 12 & 24 volt versions across our range.

A Davies Craig Thermatic Fan ‘Short’ is suitable for both air conditioning/refrigeration condenser and radiator cooling. A Thermatic Fan is the most important component on any cooling/refrigeration system. Thermatic Fans provide; strong, consistent & high capacity air flow, increased air conditioning/refrigeration performance, fully reversible blades and polarity for bi-directional air flow, additional mounting flexibility, low profile & high performance. 

Question No. 3
Can the Davies, Craig Electric Fan be installed in front of the radiator as well as in the engine compartment?
Yes. Davies, Craig electric fans work equally as well in either position. The instructions show how to install the fan blade and reverse the wiring to accomplish this. The fan blade must always turn in the direction of the arrow on the fan hub. Also always follow the instruction “This side must face front of vehicle”. 
Question No. 4
Is there any advantage to having two slightly smaller fans as opposed to the one larger fan?
One of the very important factors with engine cooling fan/s is the volume of air any specific Thermatic Fan can pull or push through a radiator. In general terms 2 x 14" fans will match the volume flow of 1 x 16” fan but not 2 x 12" fans. There are other factors including core thickness and clearly the thicker the radiator core a more powerful fan is required. Therefore a single 16” fan will out-perform 2 x 12” fans in almost all situations. E.G. If your radiator is 4 core or greater then 2 x 12" fans wouldn't be recommended. Therefore 1 x 16" fan could be sufficient.
Remembering that any Thermatic Fan will cease to be effective once the vehicle speed has reached 50-60 KPH after which the ram air takes over. We also recommend Thermatic fans be fitted to the downstream (engine side) of the radiator 

Question No. 5
How does the thermal switch thermostat controller work?
The adjustable thermal switch thermostat is a temperature control device which senses the temperature of the coolant as it leaves the engine,radiator and turns on the electric fan(s) when cooling is needed. The thermal switch thermostat is adjustable through a wide range of temperatures by turning an adjustable screw located on the controller. 

Question No. 6
I would like to place the Thermal Switch (Part No. 0401, 0402, 0404) unit in the vehicle’s cabin rather than under the bonnet. Is this possible?
No, Davies, Craig Thermal Switch (Part No. 0401,0402 & 0404) must be mounted in the engine compartment near the radiator.
The EWP/FAN Digital Controller (Part No. 8020) should be mounted inside the vehicle cabin to access the controls and feedback information away from direct sunlight and should not be exposed to excessive heat. 

Question No. 7
Can I place the probe from the Electronic Thermal Switch (Part 0402) into the water system?
The probe from the 0402 is designed only to go into the radiator fins and measure air temperature. Although you may be able to install it into your water system, the part of the probe where the wires enter the bulb is not water proof. We can't guarantee correct operation and any warranty will be void if the probe is inserted into water. This probe measures electronic resistance which is different to how a Mechanical Thermal Switch (Part 0401) water type sensor measures temperature to activate a switch. Should you want a probe that can be installed into your water / coolant system, please use the Mechanical Thermal Switch (part number 0401). 

Question No. 8
My fuse holder is melting?
Generally when the fuse holder is melting it indicates that either the wiring loom used between the fan and the switch or relay is an incorrect gauge or the motor on the fan may have an internal fault. If you have used a smaller fan than a Davies Craig 16" Fan or you have used a different brand fan before fitting the Davies Craig 16" Fan and you are using the previous fans wiring then this wiring may not be the correct gauge to carry the current our 16" fan produces. The Davies Craig 16" Fan is the only fan in our range that has a heavier gauge wiring loom than the others as it produces a lot more current than the others and requires heavier gauge wiring so the wiring doesn't overheat.

Question No. 9
My fuse keeps blowing when I use the A/C switch?

As for the fuse blowing when you use the A/C switch, this either indicates the use of an incorrect fuse or maybe an internal fault with the electric motor. You should be using a 30amp fuse in the wiring loom from the 16" Fan Kit and a 25amp supplied fuse in the wiring from the Electronic Controller.

Question No. 10
Why does my Davies Craig Thermatic ® fan have straight blades?
A fan with curved or swept blades is quieter than a straight blade fan but it does not move as much air. Also the weight of a ring connecting the tips of a blade takes power to rotate. We think it is more important to have as much air flow as possible rather than a slight reduction in noise, when the fan is running which is generally less than 5% of total motoring time. 

Question No. 11
Can I use the EWP & Fan Digital Controller to run my Thermatic Fan Only?
The EWP & Fan Digital Controller (part no. 8020) is primarily designed to run the EWP with the added function to switch on and off your Electric Fan, which saves you the cost of having to purchase an additional electric fan switch. If you are not using our EWP then we would recommend against purchasing the EWP & Fan Digital Controller as you primary fan controller as you can't independently set the cut in temp for the fan. The EWP & Fan Digital Controller is programmed to switch on the fan at 3°C above the EWP temp setting. For a fan only application we would recommend using either our Mechanical (part no. 0401) or Electric (part no. 0402) Thermatic fan switch and wire direct to the battery so the fan will run on after engine shutdown. 

Question No. 12
When installing the Thermal Switch Adaptor Kit (Part No. 0409), I found that my vehicles hose size is larger than 35mm, what should I do in this circumstance?
The 0409 kit comes with adaptors to suit inside diameter hose size of 30-35mm, if you have 36-42mm inside diameter hose then you need to use the 2 rubber sleeves over the adaptor to allow for the larger hose which are included in your kit. If you have 42-51mm inside diameter radiator hose, you can contact us and we can provide you with larger rubber sleeves to accommodate your needs.
We do not keep records on each and every vehicles top radiator hose dimensions and therefore leave it up to the customer to measure their radiator hose size and advise.

Question No. 13
I have purchased an Electronic Thermal Switch (Part 0402) but could not find any instructions about what should be done with the blue wire in the single use thermatic only section?
The blue wire from the electronic switch (part# 0402) is only required if you are running a second fan. This would normally go to the second fan relay. If you're not running a second fan then the blue wire is not required and you can tape it up or cut it off.
If you have everything else wired up correctly as per your single fan wiring set up and the fan doesn't work when you adjust the temp fully either direction with the engine temperature at least 40°C then you may have a faulty switch. We suggest before coming to this conclusion to re-check all the wiring and contact points, check the fuse in the orange wire to make sure it isn't blown and also ensure your engine is warmed up before the fan will activate. If you think you have a faulty switch then take it back to your retailer with your receipt as all our products have a 2 year warranty. 

Question No. 14
Do you sell a 6v Thermatic Fan for vintage cars?
We don't sell a range of 6V thermatic fans for vintage cars however if you were to run our fans off a 6V battery they would run at half the speed and still would provide enough cooling for a vintage car. To compensate for the reduce in speed you may consider going up in fan size? 

Question No. 15

The Digital Controller ‘Fan’ light comes on just over the ‘targeted/set temperature’ but the Thermatic Fan is not switching on?
Please check the wiring of the fan relay. The green wire with the black trace from the Digital Controller to the fan relay is a negative switching wire. Therefore from relay pin 85, this wire should be connected to the positive battery terminal either directly or through pin 30. See attached diagram. 

Question No. 16

What method do you use for plating the chrome fan blades and how does the chrome plating hold up over time?
We have been metallising Thermatic Fans for a good number of years and there have been continuous improvements to this plating process over time. The Blades and Shroud are not plastic but 66/Nylon Glass, which is a much stronger material, (no flexing of blades/shroud under hot conditions which plastic will do!), can withstand extreme heat and cold and is more durable All Thermatic Fans are covered by a 2-year warranty, including the chrome models.

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