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1997 S420
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Discussion Starter #1
Fuse #20 located in fuse panel located in the engine compartment near the brake fluid resevoir blows as soon as I start A/C in my 1997 S420. Some further information and a few problems that may or may not be related on my 1997 S420 are as follows:

1. Fuse #20 blows every time I start A/C of the car. The things listed against that fuse are Control Unit, A/C Compressor, Automatic climate control. I turned off the A/C and then replaced fuse #20 and re-start the car not working after going to workshop and reprogram the car it started and again turning on A/C the fuse blows and the car not started till reprogram and also the center lock of remote is not working after this happen but it working from button inside the car.

2. I went to many workshops no one know the reason every one saying may be wire expose problem but no one can find which wire.

3. The A/C fan is currently off for starting the car. I don't understand the issue with fuse #20 which keeps blowing.
 

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Check your gaseous pollutant sensor? The wiring on mine was bad and I had similar problems. It is under the hood in the black box that covers the ac air filter....it connects to the main wiring harness.
 

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1997 S420
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Discussion Starter #4
I tried D. man unplug the compressor, change fuse, reprogram and start the same the car started when turn on A/C the fuse blow
 

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1996 s320 swb
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465 Posts
So the fuse blows with the compressor unplugged? If so, disconnect the cooling fans, replace the fuse and try again. Might be your cooling fan relay.
 

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MY96 S500 & MY96 S600
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3,169 Posts
Bump. This is more confirmed bad wiring insulation on late model 140s. This S500 (it was blowing fuse 20) & CL600 both have it, have not checked the S600 yet.
 

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1994 S600 Coupe, 1995 S600 Coupe
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Bump. This is more confirmed bad wiring insulation on late model 140s. This S500 (it was blowing fuse 20) & CL600 both have it, have not checked the S600 yet.
I hadn't seen this thread before. Why would this cause the OP's car to not start and have to be "reprogrammed"? The original picture links are long gone. Can you get a picture of the wiring/location in question? Thanks!
 

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MY96 S500 & MY96 S600
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3,169 Posts
I can't speak of the OP, my CC certainly didn't need to be re-programmed. Pics later, car is all back together.
 

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97s420 140k miles
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2 Posts
I know this is an old thread , but I am having the same issue. I rewired the pollutant sensor, still burned the #20 fuse.
 

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1994 S600 Coupe, 1995 S600 Coupe
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1,728 Posts
Try disconnecting one item at a time, until it stops blowing. I'd start with the AC compressor. Or, take out the fuse, confirm the non-power side is shorted to ground with an ohmmeter, and start disconnecting things in the circuit until the short goes away.

Jon
 

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97s420 140k miles
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Jon
Thanks for your reply. Figured it out this morning, the blower seized up and burned itself out. $8 at u-pull and a new blower got the a/c blowing cold! Love DIY mechanics.
 
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