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1986 560SL 1986 420 SEL
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Thanks is ianrandom and mlb87560sec. I checked both the fuse in box and #5 in the fuse box. Yesterday I parked inside all day. On the way home after about a mile the blower came on perfectly. This morning after being parked in the 20 degree garage I get no blower.

Am I onto something relating this condition to temperature? IIRC there is some control that does not engage the blower until the coolant reaches a minimum temperature?

The diagram, if I read it right, shows power from the relay to an Electro is Control Unit. Is this part of the unit with the switches and thumb wheel (which I just had refurbished) or is there another black box I don't know about? Does this control stop the blower if it's too cold and in my case just not registering a warm temp?

What does the porcupine regulator do? Sorry for the maybe stupid question but it could use an answer.

All help is appreciated.

Jim
 

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SuperModerator
1986/1990 W126
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13,659 Posts
Actually, I think on your system it might be possible that it wouldn't blow while the coolant is really cold. So as not to cause extra cold in the cabin. But my cars don't have the same system. Worth checking that out, but if so it would only be for a bit.
 

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1991 500SEC sub 50K mi. 1987 560SEC Now 150K mi. 2018
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4,283 Posts
Ian is correct that the ACC fan does not run until the coolant has warmed a bit.
As I remember, the coolant gauge must come 'off the peg' some for it to engage.

MBL
From the owner's manual.
Screen Shot 2020-01-10 at 5.03.13 AM.png
 

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1986 560SL 1986 420 SEL
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93 Posts
I checked the 30 amp fuse when my problem first developed. It checked out. I'd did this using continuity check with my dmm. I did thks while leaving the fuse attached to the two screws. I was told it is best to heck the fuse removed from the holder. So I re moved it, checked it and put it back. This was all before getting the module rebuilt. Put the rebuilt unit in and as stated above still have a problem when cold. Then no blower at all. Went to check the p amp fuse again and it fell apart!

Replaced the fuse and today it is below freezing and it works.☺. I think the module was bad and I just exasperated my problem panhandling the rather delicate fuse.

All is well now and I again thank all the help from this thread.
 
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