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1988 560SL
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105 Posts
Discussion Starter #1
Going through the list of issues on my car and doing lots of preventative maintenance (TC, Flex discs, ignition coil, etc)... when checking the AC, I noticed that when I push the button to run the fan on "HIGH" the unit makes this incredibly loud noise. No noise or issues when on auto or low fan. Also, the air is not as forcefull as I would expect at high speed coming out from the middle dashboard vents (possibe vaccum issue???). Air is cold...but not ice cold. I can't believe that this loud humming-like noise when the fan is run on high is normal...any thoughts? thx
 

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2008 E320 Bluetec, 1988 560SL totalled unto death). 1997 Dodge Ram 1500, 1983 300CD
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1,342 Posts
Get under the hood

and open the cover over the blower motor. Have a new gasket on hand if it has not been opened before to your knowledge.

Inspect the condition of the motor and the well in which it is mounted. That area is a prime rust-prone space if the gasket has been allowed to deteriorate or the cover is cracked.

You can run the motor with the cover open to listen for sounds or look for bad mounts. Worst case can be rust repair and/or motor replacement. Rust repair is not easy or cheap. The motor is very expensive (up to $600.00 as I recall) if you get new from dealer. Prowl ebay as an alternative.
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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32,324 Posts
I have one of my non functional motors and fans sitting in the utility room just to try the repair this winter. Thanks GA.
The one from my '73 has plastic fans. The ones on the '72 are metal.
 

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Always Remembered RIP
1979 280sl 4 sp w/ac 1957 MGA 1998 volvo xc/70 2004 F150
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6,050 Posts
Rowdie, the blower motor on the 84 didn't work when I got it. Turned out to be a weak brush spring. I just put a helper spring from a ball point pen in it and it works fine.
 

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Registered
1987 Mercedes-Benz 560 SL
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973 Posts
I have one of my non functional motors and fans sitting in the utility room just to try the repair this winter. Thanks GA.
The one from my '73 has plastic fans. The ones on the '72 are metal.
My pleasure, bud, and good luck.

Be easy on all the black plastic pieces, especially the four mounting holes at the corners of the lower main housing. When I recently pulled mine out to replace the lower weatherstrip and spot-paint around the mounting studs, I noticed the mounting holes are beginning to get a little crumbly. Tighten the housing down very gently and evenly, use blue Loctite to keep them fastened.

Good road,
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
Joined
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32,324 Posts
Rowdie, the blower motor on the 84 didn't work when I got it. Turned out to be a weak brush spring. I just put a helper spring from a ball point pen in it and it works fine.
That is not going to help on this one. The holders on the brushes are melted. I'll post a pic when I get them out. Pretty ugly.
 
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