Evacuating the system serves two important purposes:

1 - it removes the moisture from the system;

2 - it gives you a good indication if the system is well sealed.  When I
evacuate an A/C system, I will note the pressure in the system and let it
sit for at least a few hours.  If the pressure changes at all, there's a
leak in the system.

Cheers,

Jeff

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
BenT Syncro
Sent: Wednesday, May 25, 2011 9:06 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Vanagon a/c

The system has to be a complete vacuum before you can refill. Otherwise, it
will not cool as efficiently. Even if you kept everything connected which is
highly doubtful, even sitting still the refrigerant leaks through connectors
and the hoses when oil is not circulated in the system on a regular basis.

BenT

sent from my electronic leash

On May 25, 2011, at 8:15 PM, Kevin Gilbert <kggilbert@MYACTV.NET> wrote:

> My '84 a/c parts have been removed and stored. If I decide to put the
> system back together, do I still need to pump out the system? How?
>
> Kevin
> On May 23, 2011, at 10:06 PM, Dave Mcneely wrote:
>
>> ---- David M <covrambles@YAHOO.COM> wrote:
>>> Well I have been given an ultimatum by the wife. Get the a/c fixed
>>> or get rid of the Vanagon. Its about to hit 100 degrees here in AZ
>>> so it would be nice to have working a/c again. The system was
>>> working fine around 10 years ago but lasted maybe one year after a
>>> $450 refill with freon at the VW dealer. It's still the freon (R12)
>>> system and I'm not prepared to pay the cost of regular R12 refills
>>> so it has to be a conversion to R134.
>>> How much should it cost to have this done? I was quoted a $1000
>>> flat fee by one place but that seems expensive. Is a lot of labor
>>> involved? Can a regular a/c place handle this or is the Vanagon
>>> system too unusual?
>>
>> David, one year ago I paid Bavarian Autohaus, a two man shop in
>> Norman, Oklahoma, $406.01 for:
>>
>> 1.  Leak check the system (none found)
>> 2.  Drain compressor, flush, and refill with ester oil
>> 3.  evacuate and  flush system
>> 4.  Replace dryer
>> 5.  Replace valves
>> 6.  Recharge with R134
>> 7.  Recheck system after one month for proper operation and leaks,
>> repair if needed (was not needed)
>> 8.12 months warranty on parts and labor
>>
>> That was in May last year.  I drove from here (Oklahoma) to Spokane,
>> Washington last summer, sometimes in 100 F temperatures.  The AC
>> worked fine.  It was not as cool in the van as in my air conditioned
>> sedans of various makes, but it was sufficiently cool for mine and
>> my wife's reasonable comfort.
>>
>> mcneely