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Old 05-23-2012, 06:21 AM
timmyr timmyr is offline
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Join Date: Oct 2008
Location: 1993 300E 2.8L M104
Posts: 152
“I ran the car in idle for a few minutes to check some basics:
- Fan was turning (counter-clock-wise if looking head on at the car, which seems like it's in the right direction). However, from the front of the radiator, the intake airflow felt minimal - I held up a piece of paper and it didn't seem to stick to the grill of the aux fans. From the rear, the airflow felt like it was going outward radially, not outward to the rear.”

Its possible that someone incorrectly installed the fan blade.
To check, remove the fan shroud, then proceed to remove the plastic fan blade(not the visco clutch), its held in place by three allen bolts. When you have it off , take a look at both sides , one of the sides should be labeled “FRONT.” Then reinstall the fan blade with the “FRONT” side facing the radiator.

“I turned on the A/C to high, here's what happened:
- Neither of the aux fans turned on, I believe one is supposed to?”

Both auxiliary fans should always run at the same time. The aux. fans are run on two separate circuits: one for A/C(low speed) the other for supplemental cooling(high speed). With ac on, the refrigerant pressure will increase and eventually should trigger the auxiliary fans at low speed . When engine temps get a little above 105c the auxiliary fans should come on at high speed.

Its possible that you have a fault with your low speed/ac aux. fan circuit. You might want to do some research. Unfortunately I recently lost all of my bookmarks, but do a search for auxiliary fans and Arthur Dalton, you will find a ton of info on how to test the circuit.

good luck
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