E fans wiring & ewp

Have a little project

Skoda fabia 6y with a 1.8t 20v on stock management

Due to space in the engine compartment I need to put slimmer fans (brush less spal?)

Issue im having is car has dual fans that have dual speeds

(1 fan operates with switching of AC)

How would I go around wiring the new fans without the original controller(relay)

And control a ewp do i need to have it controlled via pwm or can I have it connected to terminal 30???

Any help appreciated

Hey Khitaam,

If you can't fit a brushed thermo fan and brushless is your only option for the space you've got, you'll need to factor in control. You can't simply turn a brushless fan on with a relay. You need a dedicated controller for brushless motors, since the motor itself requires a PWM signal to run, not just a 12V feed. These controllers will also have their own systems for controlling speed, which answers your speed question for the fan side.

However, if you find a brushed fan that fits, you have simpler options for control. For two-speed control across two fans, it's common for OEM setups to use a relay arrangement that wires the two fans in series for low speed and parallel for high speed. In series, each fan effectively acts as a current-limiting load on the other, dropping the voltage each one sees and slowing them down. For high speed, the relays separate the two circuits and power each fan in parallel at full voltage.

Personally, I prefer a simpler approach: wire one fan as the first stage, switched on by a thermal switch in the cooling system (set to trigger at say 90°C), then a second thermal switch (some have two circuits built into one unit) that brings the second fan on at a higher temp, say 95°C. It won't give you true variable fan speed, but it does give you staged cooling and keeps current draw down at lower, less critical temps.

Regarding the water pump, it's not recommended to just run it direct off a constant 12V at full speed all the time, since that wastes power and overcools when demand is low. A speed-controlled setup is the better option, either through an aftermarket ECU/PDM with a fan/pump output, or a dedicated controller like the Davies Craig EWP digital controller, which varies pump speed based on coolant temperature. Worth checking the control method of whichever controller you land on, since not all of them work the same way. Most of these controllers (or an aftermarket ECU/PDM) will also let you control the fans from the same unit.

It's difficult for me to advise on wiring into your specific OEM system without more information, ideally some basic wiring diagrams of how you're planning to set things up. If you can post those, I'd be happy to go over them and give any advice.