ACC vacuum system replacement - PeachParts Mercedes-Benz Forum

#1 05-12-2004, 07:17 AM

I checked my ACC vacuum actuators last weekend, and at least 3 of them will hold no vacuum, including one of the center vents. Guess I may as well do the whole vacuum system as well as the evaporator. A couple of things I cannot seem to find in searching are:
1) How many 'y's, 't's etc are required in a complete ACC vacuum rebuild?
2) Will 15 metres of plastic vacuum hose replace every hose in the system? (just ACC, I already replaced the engine vacuum lines)
3) If I get the copper evaporator, it looks like I will separately need an expansion valve. Are there any other parts I will also need?

I am thinking about taking the old A/C hoses to the local hydraulic/AC hose place and having the rubber replaced. Any tips on this?

Lastly, should I get a rebuild kit for the compressor while I have the system depressurized? I currently have fairly cold air out of the two side vents, but since I am doing all the rest....?

...edit... this is on the 300e. I replaced the expansion valve and compressor on the 528 a couple of years ago and it blows about as cold as r134 will, which is why I will keep R12 in the Benz....

mbdoc · #2 05-12-2004, 08:18 AM

IF you are spending that much time & effort don't buy the "cheap" evaporator!! THEY are not worth saving $200!!

The vacuum lines inside the car rarely need replacement + they are color coded by application!
However the vacuum elements will.

#3 05-12-2004, 02:08 PM

Normally I stick to OEM parts, but it looked like concensus here was the copper version was more durable than the bi-metallic OEM version.

The one complaint I remember was that the copper core did not come with an expansion valve, which is why the question.

Are the copper cores cheaply made/poorly constructed, or is it a cheap design with poor fit?

mbdoc · #4 05-12-2004, 06:00 PM

The only times that we(dealer) installed the copper evaps was when the aftermarket warranty companies supplied them instead of an OE one. NONE of them fit properly & they are MUCH noiser when the compressor cycles. also they never cooled as well!

THE copper evap for that W124 chassis costs less that $100.

#5 05-13-2004, 07:52 AM

OK, so this will somewhat reconcile with the post I saw from steveb stating that he still prefered the copper evaporator cores, but his shop now installs the OEM vareity.

Am I reading this correctly that certain aftermarket copper cores require additional fitment time which is not offset by the lower cost?

Is this an issue of WHICH copper core is selscted?

Have you found ACM worth the effort?

I have not looked for lowest-cost alternatives, and after reading the glowing recommecdations for copper cores, only priced the ACM, which seemed to have several enthusiastic endorsers.

Am I mistaken?

#6 05-15-2004, 06:09 PM

Just to correct some miscommunication...

I was told at first that the copper evaporator was made by ACM. This turned out not to be the case.
Fortunately, when I ordered, I asked if he had the copper evaporator, he replied 'yes' , then I said 'I want the ACM'.
I received the all aluminum ACM with the expansion valve and rubber collar.

Now, however, as I take a break with the dash out of the car I am wondering if I read correctly.

Is it 'if you replace the vacuum soleinoid, go ahead and replace the evaporator' or is it 'If you replace the evaporator go ahead and replace the vacuum solenoids'?

The system still has R-12 in it and still blows cold enough to keep it comfortable on an 80 degree day.

The dash is apart, and the evaporator is on the table. Put it in or not? I have to go get parts. Hopefully someone will chime in in the next hour or so.

stevebfl · #7 05-15-2004, 06:45 PM

If you got it apart put it in.

You might have done too much work as my logic would be replace everything when doing the evaporator, other wise replace actuators till the one inside the case is bad. If the case comes apart might as well do all the elements.

As for which to use I agree the copper ones are tooo crude. The ACM with expansion valve and boot is the way to go.

#8 05-23-2004, 06:41 PM

I am feeling a little stupid about this.
I checked the vacuum servos individually when I got them out of the car, and only one was completely dead, although it is the one in the heater box.

But I did find the major vacuum leak; the rubber connector to the yellow check valve behind the brake bomb was completely cracked. What does this check valve do? How do I test it? If it is supposed to keep a vacuum leak from getting back to the engine, it may be faulty.

Also disturbing is the lack of oil in the AC system. I turned up the evaporator and no oil came out. Hopefully when I reseal the compressor it will have oil. Otherwise should I put in a full oil charge, or count on some being in the condenser?

And here is the obligitory photo of the event. I call it "some assembly required"