R231 SL400 Air Con Issue

R231 SL400 Air Con Issue

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mbwoy84

Original Poster:

624 posts

119 months

Monday 12th August
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Just wondering if anyone has experienced this issue before. Probably a very similar set up on numerous Mercedes models.

SL400 air con isn’t working. Press the button on the dash to switch it on and it automatically flashes and doesn’t do anything beyond that.

Only fault code states that refrigerant gas is outside of range, but it’s been leak tested, vacuum tested and regassed. I can confirm that the system definitely full of gas and leak free. Any ideas what could throw this error in this case? Not sure from which component the gas level is measured? As there are no leaks, my only possible thoughts are pressure sensor or compressor?

Any other ideas, or how to check?

MustangGT

12,287 posts

287 months

Tuesday 13th August
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Aircon can be 'switched off' by the system if the vent settings are in a particular configuration. I would check all the flap motors are functioning properly.

Deefor62

483 posts

155 months

Tuesday 13th August
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I had a similar series of events with my R231 350 a couple of months ago.
The first problem to manifest itself was poor cooling. When looking at the compressor, the rubber centre of the pulley was disintegrating. With a new compressor fitted, all was good for a couple of days, and then I had the same thing as you -ie light flashed a couple of times and then nothing.
Like yours, there was plenty of gas in the system, and no leaks. The finger of suspicion pointed to the pressure sensor at the bottom of the condensor. However, in trying to fit a new pressure sensor, the thread in the condensor disintegrated, and so a new condensor was also required.
Thankfully - all seems to be working ok now.

The pressure sensors aren't expensive, and on the proviso that the thread on your condensor doesn't disintegrate, should be an easy job to replace. System obviously needs draining and regassing in the process.

I've seen several threads on forums where the pressure sensor has given these issues.

Good luck.