S-Class (W220) 1999-2006: S 320 CDI, S 320, S430, S 500, S 600

2003 S500 AC Stopped blowing cold air

Old Oct 28, 2024 | 01:05 AM
  #1  
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Mercedes S500 W220
2003 S500 AC Stopped blowing cold air

I have a 2003 S500 with 104000 Miles. The AC was working fine for about 6 months when I recharged it partially because that is what it took. Now suddenly it stopped throwing cold air and when I tried to recharge it with freon, the gauge on it rightaway went to the RED section which should mean there is an issue with somewhere. The compressor may have stopped because of a fuse or it may have completely shut down.

Can anybody tell me is the fuse numbers are 30 & 41 as some documentation have listed it or if there is a relay that may have gone bad which is probably not easy to fix?
I did use the Red Angel Stop Leak 6 months ago to see if it fixes the condenser leak and it worked until now. It may not have helped for all I know.

Any help is deeply solicited.

Thanks
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Old Oct 28, 2024 | 11:10 AM
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From: Ball Ground, GA (N of Atlanta)
2003 S500 2007 GL450
I am sorry if my answer hurts your feelings, but this sounds like self-inflicted problems.

First - I don't think that any competent AC tech would ever recommend or approve putting any kind of sealant into your system.

Second - this sounds as if you are using one of the "recharge" bottles of R-134a, or some refrigerant mix, plus sealant, with a cheap gauge attached. If you really understand how an automotive AC system works, and particularly how a W220 system works, you MIGHT be able to add R-134a and get the system working again.

I am having a problem understanding how you could hook one of the "recharge" bottles to the so a to put the gauge into the red. The high pressure connections and low pressure connections are different, and the recharge bottle should not connect to the high pressure side. The maximum pressure that you can get on the low pressure side of the car system should be the static system pressure (system no operating) with a hot engine. When the compressor is operating, it pulls down (reduces) the pressure on the low side, so there should be no way that you could get high pressure on a low pressure connection.

All that being said, it is possible that you can get the system working again very easily. When the AC control system see very low refrigerant pressure, it disables the compressor. Recharging the system will not make it work again until you reset it.

Engine running, HVAC turned on:
Pop out the left AUTO button (small round button in the middle of the left set of HVAC buttons).
Pop out the right AUTO button.
Press in the left AUTO button.
Press in the right AUTO button.
Shut the engine off and remove the key.
Start the engine, and see if the system now works, with the tiny red LED turned off in the right set of buttons.

Let us know what happens.
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Old Oct 28, 2024 | 12:47 PM
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Mercedes S500 W220
Thanks Wally,

I do see the RED light on the right side of the controls. I had recently replaced the battery and I am sure a lot of it was reset.
The Recharge unit was indeed hooked to the high pressure (the smaller of the 2 inputs) and that is the port I have always used to recharge all the time. As soon as I hooked it up I opened the recharge button, it right away took it to the right zone which should mean the compressor is not running.. The AC was running under MAX Cool state.

Vish
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Old Oct 31, 2024 | 02:34 PM
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Mercedes S500 W220
2003 S500 AC Stopped blowing cold air

Just an update. I reset the AC using the panel where the Pop-in/Pop-out buttons are and the AC works flawlessly as before. It seems like the Red Angel Stop Leak is working just fine and the freon charge is still intact. The reason it all got reset was because I installed a new car battery and everything went back to factory defaults.
Thank God it seems to be working fine. Now if only my door locks work the way they used to work I would be the happiest guy. Had a mechanic check to find where there were leaks in the tubes in two of the doors and gave them a PSE pump to install after plugging the leaks but instead the guy tested the leaks by hooking the pump to car and burnt it. Unfortunately most mechanics don't know squat about PSE pumps. So, for the time being I am not going to worry about it. Nobody would want to steal a 24 yr old car which has a blue book value of $1100 but I must say this indeed is the best designed car out there in the world.

Vish
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