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Old Aug 5, 2021 | 05:30 PM
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Ronman
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Default Re: Heater fan going full speed all the time

Originally Posted by onehundred80
Update
Not totally convinced my tests were thorough enough I did them again and logged each reading instead of relying on memory. That was a good decision on my part. I made special leads with pins that fitted the socket holes in the wiring harness socket that fits to the regulator, the alligator clips on the other end held the multimeter probes.
The BCM from eBay was no trouble, just a bit awkward to put in. The three controllers gave almost the identical voltage out puts at the regulator socket as the one tested and logged in Jeffery Alisons bench test on the Heater/AC components.
The two regulators were both faulty, the cheapo eBay one put out no voltage at all through the range from zero to five. The original one put out .06 volts from position zero to position #1 and 7.8 volts from there to position #5.
I am now waiting for the Behr regulator to arrive and hopefully solve my problem.
Those people who said the regulator was at fault were correct, top marks to you all.
Congrats. That's why I try to buy parts with the manufacturer Mercedes used originally. The Bosch crankshaft/camshaft sensors are a good example of why. The Behr regulator at Autohaus is less than half of what I paid 6 or 7 years ago.
 
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