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I have a 1997 S500 and recently had the compressor replaced. Went to get car and it wouldn't not start. Realized the Ac control panel was not on or operational. Radio worked fine however. Mechanic checked fuses and 19 and 20 were blown. Replaced those fuses and the Ac display came up fine and the car started. Now two weeks later ingot out this morning and car won't start. Checked fuses again and both were blown. Replaced them both and now as soon as the key is turned on but before cranking fuse 19 instantly blows. The diagram shows #19 as the seat belt speed warning device. Can't understand why this would allow the car not to start. Car has always run perfectly and has never not started until now. Please help I need car back running again before holidays.
 

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Come fellas I really need some help here. 57 views all day and no response from anyone. Yet a post from just an hour or ago now has 31 replies. What gives lol. I knew this might be a tricky one.
 

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I would being winter unhook ac compressor. I don't think the started interupt relay behind fuse box would do that either.My 99 I replaced ignition switch and k38 relay.Must be something with ac since repair.
 

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Where Is This Mechanic?

It seems rather obvious this compressor R&R caused this problem. How is it the A/C didn't function after he/they replaced the compressor? Didn't they check it after they did the repair. :confused:
I'd be all over these repair folks for this. I realize Fort Worth is a big city and consumers get treated like crap at times, but still, you brought it in running, and now it's dead.

Not to be nasty, but your only 3 posts on the forum have been posted in the last 24 hours, and you demand an instant response? :wtf:
I have to say sometimes it takes a few days before the EXPERTS get around to solving these UNUSUAL PROBLEMS. If this was an obvious, easy fix, you'd already have a solution from a forum member. Nathan's "unplug the compressor" suggestion is immediate and should get you running again, but it's not really anything more than an emergency band-aid.

If I were to GUESS, this is something simple. The mechanic possible shorted a wire on the compressor or the alternator/electrical bits(which I THINK are located near the compressor) while he was making this R&R. I honestly don't know what he had to take apart to make the repair, probably disconnected the battery at the very least. I'd get that person to at least investigate this by going back over his repair area step by step till you find the short. :nerd

It sounds like you don't know a valve stem from a spark plug, AND WE'RE ALL FINE WITH THAT, but if you want help, you must be more patient. There are several forum members near you, and if you put out a distress call, and the planets align properly, you might just find one of these generous souls would pay a visit to get you back on the road. We aren't bad people or lazy, we're just humans offering our expertise for FREE. You cannot imagine how many times we solve a problem, only to never hear from the recipient again. Did you bother to RESEARCH this fuse issue using the google feature on the top of this forum? Fuse 19 has a pathway, there are probably online schematics that tell you exactly where to look for this problem. For the time being just look around the battery, the alternator and compressor for wires that may be loose, disconnected, or touching one another, that is where this old hammer mechanic would start. :devil

The reason other threads get immediate attention is that the issue is probably something that has been covered many times on this forum, and can be addressed by just about every member. I only popped on this thread because I hadn't seen another like it, EVER! I was curious about this issue and it's solution. The W140 forum isn't the most active, BTW, but you DID post your issue on the correct forum.

There are not a gazillion of these cars on the road, and the likelihood of another W140 owner being a forum member with this exact problem is slim to none for him to be on here on a Saturday/Sunday. We have an electrical wizard or two who probably could solve this issue in a paragraph. They hang out on all the forums, mostly the W124 form where there ARE a gazillion models which are in constant need of repair. FLOOBYDUST is one of these knowledgeable members. The moderators may be of assistance, also.

Welcome, bigbenzdriven! Good luck! :wave:

I will be following this thread to find out how it was resolved. We'd appreciate it if you posted your solution to share with all of us, and that you'd become a valuable, contributing member of the forum. That is how this forum works, take and give back.
 

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the ac compressor on these cars has a speed sensor or tachometer built into the compressor unit. if the belt slips for any reason, such as driving through a puddle of water, the computer will shut of the compressor. the compressor speed must match the engine speed. it sounds like your 'new' compressor may be incompatible with the system or the tach is shorted.

my clutch bearing on the ac makes a little noise and the AC guy would rather change the compressor than set the clutch gap...that leaves it up to me to fix it))


if you are blowing fuses, disconnect the ac compressor at the compressor and insert a new fuse(s) to see if that remedies your problem for starting.
 

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Discussion Starter #7
I certain was my trying to be demanding or nasty. Just really need my car to run so I can make my travels this holidays. I actually know my way around the car quite well but have never messed with a cause it has never been needed. Anyways I picked the car up running from my shop. And now it has started this. I finally got the compressor disconnected however and the car started. But it's still blowing fuse #20. I even took the side view mirrors apart and disconnected the heating elements for the glass.
 

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97 Models Had Biodegradable Wiring

I'm very glad to hear you got her started with the disconnect of the compressor. :thumbsup:

What is the build date of the vehicle?
Do you know how much if any wiring was replaced?
How many miles on the vehicle?

I read on the forum(W124 actually) that the wiring in the doors degrades from the movement in the doors. Ditto the trunk lid. There is a bundle of wires in the overhead lighting console that can trigger issues. I seem to recall folks discussing this side view mirror problem tied into fuses. Basically the 93-97 products across the model line are ticking time bombs, it seems. Anytime the wires are jostled about, they can fail.
What else is on the circuit for #20 ?

I'm thinking the mechanic did NOT disconnect the battery, since you made no mention of having to reprogram the radio code. I'm still thinking the mechanic crossed up some wiring in that repair.

If you work backwards from the items that are failed, you may find the wiring culprit. I'd also look under the fuse block, seems like I read some things about that area being problematic. I should ask, do you have the ceramic/copper fuses in place of the original plastic/aluminum?

Are you familiar with the operation of a voltage meter? That would be critical in tracking this down, IMO.

I wish someone with a lot more knowledge than myself was addressing this, there has to be a few fellas that can direct you to the solution. :help:

Apologies for my misunderstanding, I get excited when I see 3 posts and a query as to why no one is paying attention to your request. My bad.
 

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fixed

Got the problem fixed. turned out to be some weird wire with a square thing attached to it had shorted out. cant remember what it was called or where it was located. i thought i had posted about it after i got the car back long ago. but the post didn't upload. anyways i appreciate the help.

And to LogicalPosition in Sarasota FL, i do know the difference between a valve steam and a spark plug. Don't insult me! I've been working on this car and many others for many years. From oil changes, to replacing coil packs, fuel pressure regulators,engine /tranny mounts to air flow sensors oh and spark plugs. I now my around a car and the W140 quite well. Yes my mechanic disconnected the battery and yes i had to put in the radio code. he's not an idiot either like you seem to think most of us are. However, i appreciate you responding and offering your advice. but don't come at people on here with a holyer than thou and insulting attitude.
 

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Weird Wire

Got the problem fixed. turned out to be some weird wire with a square thing attached to it had shorted out. cant remember what it was called or where it was located.

And to LogicalPosition in Sarasota FL, i do know the difference between a valve steam and a spark plug. Don't insult me! Yes my mechanic disconnected the battery and yes i had to put in the radio code. he's not an idiot either like you seem to think most of us are. However, i appreciate you responding and offering your advice. but don't come at people on here with a holyer than thou and insulting attitude.

I'm glad you resolved the issue. Thanks for sharing the solution. My apologies for responding at all. :wave:
 
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