Baby, it's cold inside!

[chris.miller at infofoundry.com (Miller, Chris)]

I forget exactly, but the water expands about 1000 times as it changes
from liquid water to vapor.  So, you'd leave very little behind if you
reach the boiling point (but yes, a total vacuum is 0 left behind, and
no one will ever reach a total vac. with an a/c vac pump).

Chris 

-----Original Message-----
From: John Gates [mailto:gatesj@mailblocks.com] 
Sent: Thursday, August 04, 2005 11:41 AM
To: Miller, Chris; scirocco-l@scirocco.org
Subject: RE: Baby, it's cold inside!

This is a real good point, it will help the water vaporize, but if you
want to split hairs, if you're not pulling a nearly complete vacuum on
it you will still have vaporized water in there in a tiny amount, but
yes, this is splitting hairs.

John Gates
--
'97 Jetta GLX
'85 Scirocco

-----Original Message-----
From: Miller, Chris <chris.miller@infofoundry.com>
To: scirocco-l@scirocco.org
Sent: Thu, 4 Aug 2005 07:30:47 -0400
Subject: RE: Baby, it's cold inside!

> Jim,
>
> It may work good now, and it may continue to work well, but those 
> little $10 vacuum pumps do not completely evacuate the system, leaving

> traces of water vapor.  That combines with the 134a and turns into a 
> vicious acid (hydrocloric IIRC), and starts eating aluminum inside the

> system.  What can happen is it will work great now but in a year or
two
> the system will look like swiss cheese.
>
> Been there, done that.


Whatever kind of pump you use, try to do it with the system as hot as
possible.

At 69 degrees F, the boiling point of water is a vacuum reading of 29.22
in Hg.   Raise the temp to 104 degrees F, and you only need to suck the
system down to 27.75 in. Hg.  Doesn't sound like much of a difference,
but it is, especially with the cheaper pumps.

So, hot sunny day with the engine compartment open, or run the engine a
while and let everything get nice and hot.

Chris

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