Hey guy new too MB cars dealt with alot of them threw my time in the car business. Bought an 87 300d with 325k. Runs great one owner car. When I bought the car the blower motor worked great, cold a/c blows out of all the vents. Last week driving down the road blower motor cut out an then back in the out again. Got home checked the fuse (early 87) with the fuse in the fuse box not the separate block. Fuse 12 was melted in its block, fuse 11 is a empty spot so I moved the wires from fuse 12 to fuse 11 an replaced fuse. Does not work.
Getting 13.5v top an bottom of fuse. Tore apart blower box an jumped the
Motor it's working just fine. HVAC panel is working as I can hear the A/c compressor kicking on. Replaced the harness that goes from the blower motor to the plug behind the fuse box. Tested the motor running an I'm only getting about 3.5v to the motor. My last thought is bad ignition switch???? Any way to test it??? Please an thank you!

*early 1987 300d**

Blower motor regulator??? Bump

Those blowers are pretty simple. Unfortunately, you'll have to trace the voltage to the PBU. On the w124 Chassis, its all done by the PBU to the regulator.

Intermittant function is usually a sign of the blower drawing too many amps causing the other pieces to wear out faster. Its not enough amps to blow the 30amp strip fuse, just enough heat resistance to melt all the expensive parts.

Attached Files

Blower Regulator.pdf (186.7 KB, 65 views)

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77' 300D, "Cartman" SOLD @ 150K (didn't know what I had)
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