i just purchased a nice electric fan and i have it hooked up to a thermal sensor. i works flawless except for when i turn the car off. the car will run for aprox.3 sec after the key is in the off position. Ok now i was thinking of either intalling a high amperage diode in series from the fan. Do they make diodes like up to 20 amps? my other though would be to just install a relay . any thoughts?