Mercedes R129 blower voltage drop and contact repair
luiher’s blower motor ran on a direct supply, but the regulator connector’s 12.4 V reading collapsed to 0 V with the motor connected. After investigating the fuse supply, the owner reported restoring operation by sanding a bad contact in the part identified as number 11.
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A blower that ran on a direct supply
luiher opened the R129 discussion because the cabin blower would not work. He reported that the motor ran directly from the battery and that the regulator worked, yet connecting the motor at the regulator connector did not run it. Those are the owner’s reported checks, rather than independent confirmation that every part of the regulator circuit was sound.
12.4 V became 0 V with the motor connected
The distinctive observation was a 12.4 V reading at the connector that fell to 0 V when the blower motor was connected. The owner also reported successful motor operation using fuse-supply positive with a body ground, and using fuse-supply positive with the regulator-connector negative. He described having voltage but no “intensity”; the post gives no measured current value. The voltage reading before connection therefore needs to stay separate from the result with the motor attached.
Following the fuse-box lead
The owner asked for a 129.066 wiring diagram, then referred to M2 for the blower, N29 for the regulator and F19/15x for the supply while trying to locate the relevant front auxiliary fuse box. He asked which of two marked locations applied, and later said the location marked 1 had the same problem. These identifiers and pictures describe his investigation; the discussion does not establish a fuse-location or wiring guide for every R129. The car’s model year and engine were not specified.
The owner’s contact-repair follow-up
In the final follow-up, luiher identified a bad contact in the ignition-lock unit he called the “clausor”, numbered 11 in the attached diagram. He reported opening its rear section, sanding the contact areas and finding that it then worked perfectly. This is the owner’s reported resolution. The post supplies no sanding grade, replacement part number, post-repair electrical measurements or long-term follow-up, so those details cannot be added as a repair specification.
A commenter’s feed-wire suggestion
AdilSD suggested that the feed wire between the fuse and blower might be bad. This was a diagnostic suggestion. The later owner update reported the contact repair above; the thread does not report a confirmed wire fault or wire replacement.
Source reply ↗ · AdilSD