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WANTED W124 HVAC BLOWER MOTOR RESISTOR/REGULATOR - with cabin air filter
- Thread starter Jouser
- Start date
Oh yeah, they will oscillate and cause the motors to make weird sounds. Factory ones can fail in this manner too. Usually it's more of a high-pitched howling. When they do this it often pumps noise into the electrical system. Sometimes they cause the SRS lamps to illuminate and codes to store in random components. When it happens in 129, it almost always causes the SRS lamp to illuminate...
Findings:
The fix for this is to take a new or used porcupine syle regulator [pre-facelift, without dust filter], unscrew the 2 torx screws, toss the donor heatsink, and install onto the non-porcupine style [facelift, with dust filter] aluminum heatsink (that does not even need to come out of the car).
I have replicated this 2, soon to be 3 times on different cars with success.
No I used a regulator from a new older style “porcupine”unit. I simply separated it from the unusable heat sink and essentially plugged and played. If I remember correctly, there were some wires that were a little longer that needed to be looped and tucked in neatly so the blower motor doesn’t rub.
Arnt, the early (non-dust-filter)regulator is still available from MB, while the late (dust filter) regulator is NLA.
What JTY describes above allows facelift, dust-filter cars to use an early-style OE/Genuine regulator. Otherwise, late / dust-filter cars would be stuck using cheap knockoff regulators that generally have a reputation for short lifespans.
I did something similar a few months ago on my beater E420, using a cheap knockoff facelift regulator. The knockoff regulator was slightly larger and interfered with the plastic blower housing. I had to cut/trim a few mm of plastic to make it fit, and it just barely fit. JTY's solution would have worked much better but I didn't want to spend $300+ for a new OE regulator, and I already had one of the aftermarkets on the shelf (from a gamble I lost, buying a clearance item from RockAuto that I hoped would be OEM and it wasn't).
What JTY describes above allows facelift, dust-filter cars to use an early-style OE/Genuine regulator. Otherwise, late / dust-filter cars would be stuck using cheap knockoff regulators that generally have a reputation for short lifespans.
I did something similar a few months ago on my beater E420, using a cheap knockoff facelift regulator. The knockoff regulator was slightly larger and interfered with the plastic blower housing. I had to cut/trim a few mm of plastic to make it fit, and it just barely fit. JTY's solution would have worked much better but I didn't want to spend $300+ for a new OE regulator, and I already had one of the aftermarkets on the shelf (from a gamble I lost, buying a clearance item from RockAuto that I hoped would be OEM and it wasn't).
Thanks guys, that explains it! I've never, or luckily still not needed to do something with the blower and other things down there. I guess that is a question of time, but fingers crossed so far. Obviously depending on running time, but is it an estimated lifespan on the OE regulators? Any symptoms for a lurking breakdown?
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My diesel had 285,000 miles last fall when all of a sudden no air flow on any setting, the compressor came on but for me it happened while I was driving.
It was so annoying to not have a part that just works that I preemptively did the successful “repair” also to the other diesel I have with 318,000 miles.
The regulators are hard to get to, and that makes selling used parts really rare. All aftermarket is crap and will be noisy as hell.
Rumor has it that the heat sink porcupine design from pre face lift cars makes their regulators last longer because it does a more effective job at “cooling”.
Will keep this thread in mind if this hack ever fails me and I now have a spare and a known good working regulator or two as well!
Should be many, many years. Probably a decade or two. Failure is likely more related to hours of total use, vs age or miles.
Most common failure mode is that high speed gradually slows down. Check current draw on MAX speed with a DC clamp ammeter. With engine off it should pull 18-20A, with engine running it should be 23-25A. If it's only drawing ~15A you aren't getting max speed. When really bad the high speed will be less than 10A... almost totally failed the max speed is identical to low speed, 5-6A draw.
Total failure is where you get zero fan at all (with a good motor, fuse, and wiring). This is less common.
Forgot to mention: When swapping a regulator by removing from the heat sink, clean both surfaces and apply fresh heat sink thermal paste. This should help extend the lifespan.
This I did not do - maybe JTO helped with this on one of the cars, for the other: the new regulator came with a white pasty substance which I was happy to have some residual.
I have a complete heater unit taken out of a low mileage 500E, if you are interested. Send me a PM
