Hi,

Just tweaking the indy before she is released into the sun, had a problem last year that the fan wasnt cutting in and the indy was overheating when idling after short periods.

I wasnt running a relay last year and figured the switch wasnt capable of running at the sort of current drawn by the fan motor upon starting.

So now I am running a fan switch with a relay. Fan switch closes, energises coil and pulls in relay contacts to supply fan motor, but when I switch the engine off the fan motor cuts out. I know there is a constant +12V being supplied to one side of the switch and one side of the relay so cant see why it is cutting off instantly, anyone got any ideas?

Any help would be super dooper.

Is the supply through the relay to the fan perm postive?

Unless you have a monster fan or an exceeedingly lightweight switch you don't need a relay, if you're correct that the switch & relay both have +ve 12v when ign turned off, I can only suggets that when turning off you're removing the earth path from the relay?

Yeah both are permanent live.

This is what I dont understand, the fan switches off the instant the engine is turned off, I would expect some dead band where the temperature drops off and the fan switch takes time to open?!

The negative connection is definately permanent also, I attached it straight to my earth bar... The mystery continues.

Please forgive me if this is obvious but using a multimeter can you check volts on the relay feeds when you turn off the ignition. If they are both live, then, as has been said perhaps the earth link is broken.