When does the W124 auxiliary fan come on?
If so, where is that guy. It’s temp controlled, comes on only when it needs to. Cheers! The fan has two speeds. Low speed is triggered by the AC high pressure switch, the switch with pigtails on the drier. Jump the pigtail ends and the fan should come on.
How does a Mercedes Benz auxiliary fan come on?
Jump the pigtail ends and the fan should come on. High speed is triggered by the coolant temp switch, the one on the upper radiator hose turret on the cylinder head. Jump the contacts on the 2-pin connector and the fan should come on.
How does the low speed aux fan work?
The aux fan’s low speed circuit doesn’t respond to ambient or system temperature, it responds to refrigerant system pressure. The FSM suggests the high pressure switch triggers the aux fan at 20bar/290psi. Bridge the pigtails on the high pressure switch with the engine running and compressor engaged.
Why is my auxiliary fan not coming on?
The FSM suggests the high pressure switch triggers the aux fan at 20bar/290psi. Bridge the pigtails on the high pressure switch with the engine running and compressor engaged. If the aux fan doesn’t come on, it could be a bad relay, bad step-down resistor, bad fan or bad wiring.
If so, where is that guy. It’s temp controlled, comes on only when it needs to. Cheers! The fan has two speeds. Low speed is triggered by the AC high pressure switch, the switch with pigtails on the drier. Jump the pigtail ends and the fan should come on.
Where are the relays in a Mercedes-Benz auxiliary fan?
In addition to what Sixto has provided — There are two relays in the relay box (behind the fuses) that turn on the fan in high or low speed, depending on which switch, as described by Sixto, is activated. The relays are usually reliable. I would check the high-pressure switch in the refrigerant line first.
The FSM suggests the high pressure switch triggers the aux fan at 20bar/290psi. Bridge the pigtails on the high pressure switch with the engine running and compressor engaged. If the aux fan doesn’t come on, it could be a bad relay, bad step-down resistor, bad fan or bad wiring.
The aux fan’s low speed circuit doesn’t respond to ambient or system temperature, it responds to refrigerant system pressure. The FSM suggests the high pressure switch triggers the aux fan at 20bar/290psi. Bridge the pigtails on the high pressure switch with the engine running and compressor engaged.