Fuse#6

[lystgl]

#6 fuse blows about a minute after starting blower fan no matter if on high, low or auto in 560sl. Blower motor and pre resistor work fine when removed and poered by 12v separately. Thinking it might be blower module N29/1 as #6 fuse goes directly to #12 on module? Any thought anyone?

[Frank Reiner]

The fault is likely in the A/C compressor circuit (relay N6, fuse 6).

[lystgl]

Thanks, I'll give it a look

[Sugar Bear]

Disconnect the compressor at the clutch to see if the fuse stops blowing. If it does it is likely a failing clutch.

[lystgl]

Had the relay out. Had ohm resistance readings from #15 pin to all the others and from #31 to all the others however I could not get the relay to "click when power was applied to #15 and 31 or 15 and KL. If I put the relay back in it's socket with the N29 out (it's at a local electronics shop for a looksee) the fuse does not blow when the key is on and blower and AC on full although nothing's working like the blower etc since the N29 is out. There is an audible click when the key's turned coming from one of the relays in the glovebox / dash but haven't a clue if it's actually this one or not. Thoughts?

[lystgl]

Real dilemma now. Electronic shop said the N29 had issues, would cost $320 to repair with no guarantees. Opted for a used one instead. Put it in and fuse blew again. Now have a used Klima relay coming. Had removed the two wires from the high / low pressure switch on the receiver dryer to prevent compressor from running (easier to get at than clutch switch?) but fuse still blew so hoping it's the Klima relay! German technology. Even 1987, way beyond my abilities

[lystgl]

Got new used Klima Saturday. Installed today, fuse still blows even when on defrost and full heat with high / low pressure relay on receiver drier unplugged so compressor could not start. Ordered new blower motor from ******** now. Anyone, anyone take a little pity on a not at all electrical / mechanical old age pensioner and give the guy a pointer on where to go next?

[Sugar Bear]

Did you try unplugging the AC clutch to see if it stopped blowing the fuse?

[lystgl]

Yes and it did! Disconnected it at receiver / dryer. Initially, I'd disconnected the wrong one. Auxilliary fan motor! I still have the original R12 in the system. Would like to keep it original. I live in Canada. The 134A refrigerant is not available here. Not enviro friendly enough I suppose. We have R12A, a flammable mixture and not as efficient either. What's the better way to go? Compressor cw new clutch drier etc. or chance just a new clutch? Either way, think it's going to entail a freon change and from a labor standpoint, replacing the compressor unit might actually take less time?

[Sugar Bear]

Just to be clear the fuse does or does not blow with the compressor clutch unplugged?

Which compressor model?

If the clutch is causing the problem and the AC system works well I'd replace only the clutch. It may be able to be replaced without removing the compressor.

[lystgl]

With the high low switch on the receiver dryer unplugged the compressor clutch does not activate. I have another problem however. I'm told I should not be getting any power through those lines as the Klima relay is supposed to detect that the low and high pressure relays are unplugged, and not send power for the clutch? Geez! And I thought maybe I'd gotten to the crux of the thing and just had to decide on new clutch assy or complete unit? Now I'm told there's a short somewhere causing these lines to power up.I'm not sure of the model of compressor. It's awfully tight under there with a lot of grease, oil and dirt. It's 1987 560SL. Did they use more than one kind of compressor?
I can't even find where the wire from the clutch terminal goes to put a multimeter in between to read amperage. I do love these old cars when they're working though. lol

[lystgl]

Oh yes, and the fuse does not blow. This despite there being power there that shouldn't be?

[Sugar Bear]

If the AC cooled well and the compressor sounded good replace just the clutch and the drive belt if it slipped or burned at all.

The compressor should be a 10P17C, use high quality new (not rebuilt) replacement parts,

[lystgl]

Ok, I'll see what I can find for compressor clutch. Do you think it changeable without removing compressor itself? If so, I hope to leave everything else as is, intact and not have to take it to have the R12 removed at all!

[lystgl]

By the way, thanks for your interest and help!