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  #1  
Old 09-15-2008, 08:43 PM
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another aux fan no go

the '85 SD's aux fan runs fine connected direct to battery but not otherwise.
Yes i shorted the temp switch on the drier, yes i checked the fuse (replaced with new) yes checked relay (replaced with known good one).
Any further things to check? Thanks.

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  #2  
Old 09-18-2008, 03:16 PM
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Try the other temp switch

I believe the temp switch on the drier controls the compressor. The temp switch that controls the fan is the one on the thermostat housing.
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  #3  
Old 09-18-2008, 03:20 PM
1986 300sdl 1985 380se
 
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I believe the pressure switch on the drier also controls the low speed fan setting and the one on the thermostat housing controls the high speed fan setting. There should be two relays, low speed and high speed.

John
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  #4  
Old 09-18-2008, 03:21 PM
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mmmmmm Diesel...
 
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The drier has two switches, one pressure switch that controls the compressor. The other is for the Aux fan.

You can remove only temp switch with out loss of freon.
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70's SPM #5608 Fairmont A-4 MOW car

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RIP--Lost in fire...82 300D 322K was My Daily Driver-On the search for a w126 now...

90 Dodge D250 5.9 Cummins/5 speed. 350K
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  #5  
Old 09-28-2008, 10:27 PM
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Closing in on it

I see up to 12.7 volts at the fuse. But only between 9.7 and 10 volts at the drier spade connection (before the drier) and between 9.7 and 10 volts at the socket where the fan plugs into. I assume that's why the fan won't run. Any idea what might be causing that?
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  #6  
Old 09-28-2008, 11:17 PM
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Check continuity across the low speed resistor.

Sixto
87 300D
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  #7  
Old 09-29-2008, 11:33 PM
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No continuity

across the resistor, it seems. The place where they put it you'd think they thought it would outlive the car and never need replacing. Any tips on how to get it out and a new one in?
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  #8  
Old 09-30-2008, 02:08 AM
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If it's behind the headlight, easiest to pull the headlight.

Sixto
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  #9  
Old 09-30-2008, 02:18 AM
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Oops, I guess from the other thread yours is under the brake booster. I don't know how to get to that other than with a a Philips bit on a u-joint and really long socket extensions.

Sixto
87 300D
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  #10  
Old 09-30-2008, 01:22 PM
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Unhappy resistor replacement

Looks like the 124 uses the same resistor. Can the beige part be unclipped/unsnapped from the black bracket or do you have to remove the whole thing?

Pics show what 126 owners have to deal with to get to it
Attached Thumbnails
another aux fan no go-resistor.jpg   another aux fan no go-res-loc1.jpg   another aux fan no go-res-loc2.jpg  
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  #11  
Old 10-01-2008, 12:27 AM
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You might be able to pry the bracket open but I doubt you can do it with the bracket screwed in place.

Sixto
87 300D
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  #12  
Old 10-01-2008, 08:19 PM
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Well, anyway, your bad resistor diagnosis was spot on. Ran a wire between the two terminals to bridge it and the fan started right up. Thanks for that.

Unfortunately have bigger fish to fry now: Just lost 2nd 3d and 4th gear while testing the kickdown on the highway. Time to start a new thread.

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