Join Date: Mar 2002
Location: Austin, TX, USA
Re: Fan relay won't shut off
Sometimes cheap relay contacts can weld themselves together when subject to high currents. You probably should put a volt meter on the coil leads of the relay to see if it is in fact energized. The other possibility is that the relay is miswired. Most relays have a normally open and normally closed contact. If you happened to get it backwards, the fan would run all the time until you reached temp and then shut off.
BUT, typically the relay is supplying battery power to the fan when an IGN source and temp switch energize the relay. The fact that you say it comes on when the key is on is sounding like a wiring problem ahead of the relay, or a bad temp switch. Hopefully you don't have your relay powered by an IGN source. That's a lot of current for an IGN supply to handle not to mention the load on the IGN switch and wiring.
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI