Amazon: electric fan wiring harness Amazon: electric fan wiring harness. Skip to main content. Dual Electric Cooling Fan Wire Harness Kit 185 On 165 Off Thermostat 50 AMP Relay NEW. 3.5 out of 5 stars 6. $32 $ 32. 99. Get it as soon as Mon, Apr 22. FREE Shipping by Amazon. Painless 30101 Thom Electric Fan Relay Kit. Electric Cooling Fan Wiring Harnesses Wiring Harnesses. If you've purchased one of our radiator kits with dual fans, then this is the fan harness you need to wire your new cooling fan up without headaches and reliability issues. After over 20 years of building radiators with electric cooling fans, we've leanred a lot about problems that can creep up in electric fan installs.