no aux fan spin, fan relay? - Mercedes-Benz Forum
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post #1 of 2 Old 08-10-2005, 07:44 PM Thread Starter
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no aux fan spin, fan relay?

on a 1980 300sd i can hear the fan relay click when grounding the temp switch, i get 12v at the fan but my fan does not spin. if i connect the fan directly to the battery it spins. the car loom clip at the fan when disconnected from the fan has good ground. the fuse is good.

is it possible the relay just cant pass 12v under a load but will show 12v with no load? seems unlikely...

anyone know the part # of this relay if it is the culprit?

also, does this fan only come on when the water gets to a certain temp or should it come on other times too? for instance when i turn on the a/c?

does anyone know the temp the switch should close at? how do you test it when it isn't hot out?

thanks a lot!
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post #2 of 2 Old 08-12-2005, 12:05 PM
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I'm not really certain what your cooling system's wiring is like offhand, but I THINK that it is like what I have on my 124's. There is a high speed cooling switch on mine that turns on at 105 degrees C. Also, there is a pressure switch on the reciever/drier that will turn on the fan.

I think the relay in question may be interchangable with others in your car if you want to swap them out for testing.

\'87 Mer-B 300D (220,000 miles) (sold)
\'93 Mer-B 300D (173,000 miles) (sold)
\'87 Porsche 928 (101,000 miles)
\'98 Dodge Ram quad-cab (250,000 miles)
\'2001 CLK430 Cabrio (50,000 miles)

Past cars: 1969 mercedes 250, 1981 300D, 1972 220D
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