Date:         Tue, 10 Aug 2010 17:04:15 -0400
Reply-To:     Ed McLean <email99@BELLSOUTH.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Ed McLean <email99@BELLSOUTH.NET>
Subject:      Re: Replacing pressure A/C Pressure switch w/o losing Freon
Content-Type: text/plain; charset=ISO-8859-1

Actually I do have a modified super-duper heavy duty A/C system with two
condensers (cooled by three fans) and two evaporators.  But that's a
different story altogether and unrelated to Mr Sullivan's system.

I based my calculations the 1991 Vanagon air conditioning system R-12
refrigerant capacity, as published on the back cover of the Bentley manual.
 I made no assumption that this system had been modified in any way such as
the conversion to r134a.  The capacity of the system is 1450 grams of
dichlorodifluoromethane, MW 120.91 g/mole.  This is 11.99 moles of
refrigerant which, by the ideal gas law calculation, occupies 268.6 liters
at Standard Temperature and Pressure.  STP, as we all know, is 25º C and 1

Atm pressure.


I hope everyone knows that the second paragraph is written a bit in jest
although it is correct and my reply is just a chance to flaunt my A/C system

that works quite well.   Jeff, thanks for the reply.


My original post was very serious, however.  Compressed gases are very
dangerous when not handled with great caution.  I enjoy Michael's letters
far to much to see him, or anyone else, embarking on an exceptionally
dangerous task without fully understanding the hazards.


Cheers to all,

Ed




On Tue, 10 Aug 2010 16:00:41 -0400, Mike S <mikes@FLATSURFACE.COM> wrote:

>At 03:28 PM 8/10/2010, Jeff Schwaia wrote...
>>"270 liters of oily freon gas"...  You must have the optional
>>super-duper,
>>heavy duty A/C system!  ;-)
>
>R-134a weighs ~4.25 kg/1000 liters at atmospheric pressure and room
>temperature, so 270 liters is about 1.15 kg of freon. VW says the
>Vanagon holds 1.35 kg of R134a, so really, he must have the
>slightly-shrunken, light duty system.