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1983 500SL
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11 Posts
Discussion Starter #1
I’m in need of some help I just picked up a 1983 500sl and the AC is not working. It will randomly turn on but then it shuts off after a few minutes. I tried high low all of the different buttons and temp settings. Now I can’t get it to turn on at all when I push the top/ bottom button (second from left) I can hear something clicking on behind the glove box, I get the same thing with the button for bottom vents. When I push the fan button, high or low I don’t hear anything and no air comes out. I’m not sure where to start anyone have any suggestions?
 

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Premium Member
1983 380SL, 2000 S430, 1991 420SEL (retired) - RHD
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5,520 Posts
Clicking sounds like a relay. I'm not sure if yours is behind the glovebox. Unfortunately , there are multiple possibilities but I'd change the fuse and check the relay first.
 

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1983 500SL
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11 Posts
Discussion Starter #3
I check the fuse again I check it not to long ago but that's when the air would turn on for a minute. Where is the relay located?
 

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1986 Mercedes 300SL r107
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179 Posts
As strange as this sounds, I was having similar problems with the fan settings in my car (except AC) took me a while to figure out but the ignition in my car goes about 2mm to far, when it is turned back to the proper ignition point the fans work as they should, worth a try before you rip everything apart


Sent from my Autoguide iPhone app
 

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1978 450SL Astra Silver on Red Leather
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24 Posts
blower motor, check that it has power to it and its working. when mine was seized the compressor would cycle on/off while all relays were clicking. i tore apart my dash checking relays and solenoids before i checked the blower motor.
 

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Premium Member
1983 380SL, 2000 S430, 1991 420SEL (retired) - RHD
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5,520 Posts
Fuses

I check the fuse again I check it not to long ago but that's when the air would turn on for a minute. Where is the relay located?
Be careful with the fuses- the alloy (silver color) ones can fail without being burnt. Copper/brass are best.
I think the relay is on the firewall inside- behind the glovebox. You have to remove the glovebox. 83-680 in the manual.
 

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1983 500SL
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11 Posts
Discussion Starter #7
I checked the fuse it is a copper brass fuse and it's good. I will check the fuse tomorrow. Is the acc system close to same as the 1983 380sl? I'm asking because I don't have a manual for the 500sl.
 

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Premium Member
1983 380SL, 2000 S430, 1991 420SEL (retired) - RHD
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5,520 Posts
Manual

I checked the fuse it is a copper brass fuse and it's good. I will check the fuse tomorrow. Is the acc system close to same as the 1983 380sl? I'm asking because I don't have a manual for the 500sl.
Then It's not the fuse.You should check the relay. It could still be other issues like noted above- the blower motor controls or you master unit or.........

My aircon is completely different (RHD). However,you can download a freebie manual in the "sticky" section of this site.I think that reference I gave you is ok for US models.
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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32,345 Posts
It sounds like you have the ACCIII system. I am 99% certain it is the same as the '82 up 380SL. Check the on line service manual.
 

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1983 500SL
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11 Posts
Discussion Starter #10 (Edited)
Yes it is an ACCIII, I really appreciate all the help and advise I'm frying here. I'm going to try to get off of work early today so I can test the relay. Is there anything else I could check at the same time? Also, I know I'm jumping ahead of things but I read on here that on the compressor the clutch will not engaged if it is to low on freon. Is the a way I can check to see if the clutch is seized or not?
 

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1983 500SL
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11 Posts
Discussion Starter #11
I tested the control relay and I'm getting voltage on all of the pins. I put one end on pin 12 and the second pin on each of the other eleven pins. I then ran a jumper from pin 12 to pins 3- 7 and got different speeds from the fan. What do I need to test next to know if it’s the control relay or the buttons on the acc controller?
 

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Premium Member
1983 380SL, 2000 S430, 1991 420SEL (retired) - RHD
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5,520 Posts
Over to the others- can't help with ACC. However I have read a lot about solder joints needing repair in the main control unit.Do a search on it - there's a lot of threads.
 

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1983 500SL
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11 Posts
Discussion Starter #13
Over to the others- can't help with ACC. However I have read a lot about solder joints needing repair in the main control unit.Do a search on it - there's a lot of threads.
I did a search for the solder repair and I can't find anything showing or telling how to do it. Can you point me in the direction or post a link?
 
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