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Mercedes W123 Over-voltage Protection Relay and Fuse Replacement

  1. Mercedes W123 Over-voltage Protection Relay and Fuse Replacement, Over-voltage Protection Relay and Fuse: crwdns2935265:01crwdnd2935265:01crwdnd2935265:01crwdne2935265:0
  2. Mercedes W123 Over-voltage Protection Relay and Fuse Replacement: crwdns2935265:02crwdnd2935265:01crwdnd2935265:01crwdne2935265:0
    • Look up inside below the dash, just beneath the furthest right side dash vent. You'll see the OVP relay with the red ruse on top.

    • Even if you are just checking the fuse, the easiest way to get access is to remove the entire relay. Simply pull it up and off of the black plug it is attached to, which sits beneath it.

  3. Mercedes W123 Over-voltage Protection Relay and Fuse Replacement: crwdns2935265:03crwdnd2935265:01crwdnd2935265:01crwdne2935265:0
    • This is the OVP relay out from under the dash.

    • The fuse on top slides in side-ways. It is a 10 amp fuse.

    • You can use a needle nose pliers to pull the fuse out of the holder that is attached to the relay.

  4. Mercedes W123 Over-voltage Protection Relay and Fuse Replacement: crwdns2935265:04crwdnd2935265:01crwdnd2935265:01crwdne2935265:0
    • As you can see here, the fuse was blown. The filament is broken internally.

    • Since this was the case, the fuse was replaced. The tachometer returned to normal function indicating that the fuse was the problem.

    • If the fuse continues to blow, the OVP relay may need to be replaced. If the fuse is not blow, you may need to test and/or replace the OVP relay.

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To reassemble your device, follow these instructions in reverse order.

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Nicolas Siemsen

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Community

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Hi,

Thanks for the tutorial, does this apply to 1986 560sl?

Thanks,

Patrick

pepe - crwdns2934203:0crwdne2934203:0

Hi guys just want to know what amp's are the 2 fuses

By the relay under the hood..thanks in advance

Charles Lottering - crwdns2934203:0crwdne2934203:0

Hopefully this is my issue. I live in the San Joaquin Valley in California and my 1981 Mercedes 240d is my daily driver. The compressor was working but we are trying to get the auxiliary fan to come on when the AC comes on otherwise it doesn't cool properly. I replaced the radiator fan with an electric and didn't realize the auxiliary fan is not working so the AC would only start cooling when the electric radiator fan would kick on. When we were trying to see how to jump from the AC relay to the auxiliary fan relay we must have over charged the system and tripped the fuse because now the compressor won't engage.

Dan Hazen - crwdns2934203:0crwdne2934203:0

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