BenzWorld Junior Member
Date registered: Apr 2010
Vehicle: 1985 380SL with 66,000 miles I am the second owner
Location: Ocala, FL
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Richard, if the one prong did not make the fan come on then you have a problem either with the wire going to the relay or the relay. Sence it works with the two wire I would think that the relay is working from there. I think that you have to check the relay and the wire coming from the one prong sensor to the relay. Grounding either one of those sensor should make the fan come on. If the wire check out good then you will need a new relay. Now just to make sure we are all on the same page: the one prong sensor is on the intake manifold and the two prong sensor is on the drier for the AC. The one prong is program to come on at a set temp and the two prong is set to come on with the pressior on the high side get to a preset pressior. I looked at the wiring diagram and both of the leads go to the same pin on the relay, which tell me that you have a open wire from the one prong sensor. Good luck Jerry
Last edited by Ocala450SL; 06-02-2010 at 01:36 PM.