My '78 300D blower motor (ACCII) will not run very fast on the High speed setting. It runs, but much slower than normal and it's not pushing enough cold air - just started a week or so ago. I know the fan has 3 variables on the HI setting (I think ???) - but what all controls the speed? Thanks.

BTW, it was 106 here today!

ryan

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RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE

The blower motor could be going out. Mine did that just before it started blowing fuses. Check amperage draw first.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Might be the brushes; pull the blower to see. There's a set of power resistors (coily wires in a ventilated metal box) on the passenger-side inner fender but they should be out of the circuit on high speed.

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

I believe that silver box with a coil under the hood controls the fan speed. I made a how to on replacing the brushes if that is the issue. You can find it in the DIY articles section.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine