The coolant temperature sensor is located on the front of the engine at a 45 degree diagonal toward the front from the oil filler cap. My resources don't mention a fan relay, but that doesn't mean there isn't one. Relays are typically large square components similar to the picture I have attached. They are also usually located in a relay center under the hood. On Mercedes there are two: One by the bulkhead at the rear of the engine compartment and one up front by the battery, just behind the driver side headlight assembly.
Saturday, September 17th, 2011 AT 8:44 PM