Paul, You know the fans are good. If so, make sure all the connectors are making good contact. Then short out the otterstat/temp switch in the lower left hand water pipe with something. If that doesn't turn them on then check the voltage going to them thru the circuit breaker. The brown wire going into fan relay should read 12 volts. It's hot at all times. coming out of that and going to the circuit breaker is the brown/orange. Then it goes to the Fan fail circuit. It any of those components are original you may want to consider an upgrade. Look for any broken wires or ungrounded fans. John Hervey www.specialtauto.com