I don't know the answer to your question but what I did was pull three pins and bimetallic strips from three different E320/300s from the junk yard. All of the bimetallic strips were the same, one of the pins were shorter. Mine was the same as the other pins so I plugged in the shorter one and that seemed to work.

Not very technical I know, but my fan would spin freely and stop under pressure before. Now it runs strong enough that I can't safely stop it with my hand. Chopped up a hot dog pretty good! It's not roaring like what others say they do but it's keeping the temp under the 100C mark.

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94 E320 and 84 380 SE now - past Mercs include 68 280 SEL, 74 240D, 77 240D, 80 300D, 84 190E