got a DS in a trade and the fan doesnt work. I put a fan from another DS on it and it still doesnt come on when hot. What controls the fan and where is it?

 

Drill a hole in the tank cover plastic right above the thermostat. Put a toggle switch (from checker or any parts store) in and connect the 2 wires from the sender. When you install your fans make sure all the bolts around it are equally tight, If not it will put a strain on the fan and make it fail quiker. Just make sure the blades on fan are moving freely. To check to see if fan even works, run a wire conecting the 2 wires that go into side if thermostat and sender.