Air-Con Troubles

[suttonmills]

Howdy all, I've tried this elsewhere to no avail so I'll give some of you technical lads a shot,

Ill try and keep this short and sweet but basically something that has been on my list of things to do for a while is sorting out the AC compressor on my beloved 08 E320 CDI.

Essentially, the engine gives off a whine which mysteriously stops when you turn off the AC. It is also worth mentioning that I have been a little unimpressed with the performance of the cars AC with really lacklustre temperatures being spat out, particularly on very hot days. A re-gas has been on my list of things to do, but I didn’t want to pay for a re-gas, just to have to do it again upon replacement of the AC Comp. Remember this for later.

The novelty of pretending the whine is coming from a supercharger is beginning to wear off so I’m wanting to get to the bottom of it, and ideally I’d like to avoid forking out for a new AC compressor if at all possible.

While investigating the possibility of the noise originating from an easily replaced clutch assembly, I stumbled across STAR bulletin S-B-83.55_87f
Now… Due to the fact that the noise stops when you turn off the AC, my thoughts are that it cant be the pulley because the pulley baring is always engaged whether the AC is on or not, which is further confirmed by:

"If there is a whining noise that is RPM-dependant which is present with the air conditioning on AND off and is determined to be caused by the tensioner pulleys, guide pulleys or refrigerant compressor, continue with step 5."

(correct me if I’m wrong)

At this stage it wasn’t looking good for the whole avoiding the purchase of a new comp. thing, until I saw this:

" If there is also a cooling performance complaint, the noise could be caused by low refrigerant level, perform a Refrigerant Circuit Test as per SDS and follow instructions for corrective actions."

So my question is, what do we think?

1. Do I stop being a pauper, hope the gods of Stuttgart are shining down on me, get a re-gas and just eat the cost if it doesn’t work?
2. Do I crack on with a pulley replacement (DIY jobbie)?
3. Do I concede, put on my big boy pants, book in at the indie and spend the missus’ holiday fund on a new comp and kill about 7 birds with one stone?

I now realise this wasn’t short nor sweet. I apologise.

Cheers, Jack.

 

[Notamech]

I would say take it to an experienced merc indie. This way they may be able to lean on their experience to advise you whether it just needs a regas or pulley or everything. If its common to hear a whine due to low gas i expect they would know this. I think its never a good idea throwing money at parts unnecessarily and sometimes the simplest solution works wonders. I had a timing chain rattle on my car and just changing the oil sorted it. Else from reading online, to me it seemed like i needed a new tensioner or chain even which was an expensive job.

 

[Petrol Pete]

Hello and welcome . Don't forget it's not just refrigerant that is in the system their is PAG oil as well. A proper 're gas' (full AC service by someone who knows what he is doing) will add the correct amount of oil , it's what lubricates the pistons in the pump.

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[Benzowner]

Try and find an auto air con specialist, probably cheaper in the long run rather than just see if this will fix it

 

[Smiley]

As above find a local AC specialist; otherwise you will be guessing. Ime its 50/50 whether a regas fixes it or something else is needed. If it is in need of a regas and you keep running it "dry" then you will do more damage.