Inline Fuse on a HVAC Blower Motor
 

About 2 years ago I decided to put a inline fuse on both the auxiliary water pump and the HVAC blower motor on the w123. At the time I didn’t have a 16 amp fuse for the blower motor, but I did have a 30 amp and decided to use it. Sealed it up dash and forgot all about it.

Fast forward to today. No air coming out of the vents. The blower stopped working.
Looked at the fuse block. Every thing looks good.

I opened up the bottom of the dash…

http://www.peachparts.com/shopforum/...1&d=1294361736



and look what I found…. Yikes!!

http://www.peachparts.com/shopforum/...1&d=1294361751



Obviously I have a faulty blower motor which needs to be replaced or repaired.
I believe if I didn’t have this inline fuse, my main fuse box would have been totally melted. I think if had remembered to replace the 30 amp fuse with a 16 amp, the fuse holded wouldn’t be toasted also.
I'll fix or replace the motor and put a new inline fuse. Hopefully I'll get this going soon and not be in the cold!


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I would try the motor before deciding to replace it. You may have just melted the fuse holder due to a bad connection. It doesn't make sense that the 30 amp fuse would blow before the 16 amp fuse in the fuse box.

It makes some sense to me. It's basically a direct shorter path from the blower, where else the surge would have to travel through resistors, switches and etc to make it to the fuse in the main fuse block. I think the large surge just stopped at the fuse link.


http://i252.photobucket.com/albums/h...123_Page_1.jpg



I'll open up and test the blower motor to see what's happening.


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It's possible. It's also possible that there was no short and the fuse wasn't making good contact with the fuse holder so it eventually heated up and melted with normal current.

+1, electrical connections must be tight and clean especially for high amp circuits otherwise the connections can get really hot and melt what's around it.

Totally agree with you fellas. It is important that connection is clean and good.



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So I took apart the blower motor and this is what I found. I haven't tested it with power, but this might be the problem. The wire appears to have been rubbing against the inside of the cage fan and then arching to the housing.


http://www.peachparts.com/shopforum/...1&d=1294420534



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Great thread Richard. Glad nothing happened.

If you decide to make these blower motor inline fuses, like what you did for the auxiliary water pump, put me down for 1! :)

That may be the problem, if the bare wire was close enough to the metal motor housing. Hopefully it's an easy fix and you don't need to replace the motor. Last time I replaced mine, I had to buy the entire assembly (about $700) instead of just the motor.

Recycled for new members
 

Recycled for new members

Since this is bumped, I like to make an update.

I ended up shrink wrapping the exposed wire and the blower motor works perfectly. I also made a new fuse link to replace the melted unit. Still the 16 amp ATC blade type fuse is not readily available, so I have been using a 20 amp fuse. The fuse holders I have been using are rated up to 30 amps.


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Question
 

Are you making these for sale, if so how much?


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Yes I do make these for sale using salvaged connectors. The blower motor units are $15 shipped.

http://www.peachparts.com/shopforum/...orfuselink.jpg



I also sell the Aux pump units for $17 shipped. Payments via PayPal. Multiple units purchased gets a break on shipping cost..

http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/242553-1-amp-fuse-link-w123-auxiliary-water-pump-%96-plug-play.html


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Just a note that the price (of both the blower motor unit and the similar one for the auxiliary water pump) is well worth it, not only for piece of mind, but also for the trouble involved in making your own... x2 if you are not used to working with wiring and connectors.

I made one for the pump on each of my cars and will be THRILLED to pay DV for others for the blower motors. Suffice to say that my versions are a bit less, err, OEM in appearance.... :D

Thanks for the comments! Very nice.