Date:         Thu, 28 Jun 2001 00:37:47 -0700
Reply-To:     DaveC <voicebox@DNAI.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         DaveC <voicebox@DNAI.COM>
Subject:      Re: A/C useless when over 100 degrees
In-Reply-To:  <3B3A4A35.2F97B267@aros.net>
Content-Type: text/plain; charset="us-ascii" ; format="flowed"

> > The a/c in my Vanagon seemeed to work fine in 90 degree New York.
> > But now I'm in AZ, it just cannot cool a hot van on a 100 degree day (which
> > is everyday right now).
> > Is this an inherent weakness or does my system need looking at?
> > Anyone else in a hot climate got his a/c working well?
> > My '95 Mercury Sable has no problem cooling (almost instantly) in the same
> > conditions - and its 134a, not Freon.
>
>One thing I do know is that refrigeration air conditioning is not as
>efficient out here in the dry desert heat. Since the task is to remove
>moisture, its hard pressed to find any out here :-) I might guess that
>your car has a smaller interior, and is better insulated? <shrug> Just a
>thought

I don't own a Vanagon, yet, but I've had experience maintaining the
a/c systems on several cars, some in the S. Arizona desert (S.W.
USA), and some on N. California coast. Some of these observations are
generic -- applicable to all R-12 systems, while some are not. Please
excuse the few errors (does a Vanagon compressor have an adjustable
hub-to-pulley clearance?) that do not apply to Vanagons.

The primary function of a/c is to transfer heat. It is a heat pump.
Condensation (removal of moisture) is a byproduct of this process.
Actually, because of the natural moisture on the surface of our skin,
dry air feels "colder" than humid air because of its ability to hold
more moisture than moisture-laden air. This makes it better at
evaporating moisture from our skin, creating a mini "windchill
factor" effect. All this is moot, however, when the a/c's efficiency
tops out in the 100's.

The Vanagon is a huge volume of space. We love this fact 3 seasons of
the year. This fact, plus the huge glass area of the vehicle combine
to make that 4th season a bummer in all but Alaska.

Every "ounce" of heat you can keep from getting inside the vehicle is
one "ounce" less you have to remove.

If your windows aren't tinted, seriously consider it. A silver/bronze
reflective tint makes the vehicle cooler than having the windows
tinted dark (smoke, gray, green, etc.). The sun's infrared rays are
reflected by a shiny surface; a dark color, while blocking the
infrared rays from getting into the car's interior, will absorb them,
heating the glass. There is a small heat difference between the two
tints, but in a car as large as the Vanagon, every bit counts.

Making the roof of the vehicle somehow reflective also contributes to
making it cooler. (The factory white of the Westfalia is good, but it
still absorbs more infrared (ie, heat) than does a metallic "silver"
material. Don't use silver paint as a reflective material; it doesn't
do any better than the existing color.)

Insulate, insulate, insulate, wherever possible. Door and window
seals and crannies between panels should be airtight. If you can hear
wind-roar, you're probably losing BTU's.

R-134a, with an R-12 compressor, in a marginal climate (read: as hot
as it can get) is not a good choice. If converting to R-134a, old
r-12 hoses are not designed for the increased pressure that develops
from the use of R-134a which, I believe, is about 120 - 140 psi
higher. So additional costs (especially those looooong Vanagon
hoses...) must be calculated.

I have heard that Freeze12 is a good, inexpensive (us$8/can, last I
looked) alternative to R-12. Freeze 12 costs about the same as R-134a
and requires no modifications for older cars and there is no
noticeable decrease in cooling efficiency. The cost is the same as
R-134a because it is a blend of 20% R-142b and 80% R-134a. It has
about the same pressure curve as R-12 but the problems with being a
blend is that if/when one component of the blend leaks out it leaves
the ratio changed so instead of topping off you have to evacuate and
recharge entirely (or so I'm told). Check out http://aircondition.com
for more info on R-12 replacements.

An a/c "checkup" is always a good idea. Find someone who is highly
recommended by a competent mechanic. Ask people you respect. Get more
than one referral. Simply being able to pour refrigerant into a
system does not a fine a/c technician make. A few possible problems
(excluding a major leak) are: misadjusted compressor belt; too little
refrigerant (some times shows up as bubbles in the sight glass); too
much compressor oil (resulting in less room for refrigerant); old
expansion valve; improper compressor clutch (pulley-to-hub)
clearance; malfunctioning condenser fan.

Check the condenser (behind the grille) for obvious problems such as
blockage from debris, bent fins, etc.

Probably the simplest thing you can do to keep your a/c system in
good shape is to use it year 'round. The reason for this is to keep
the shaft seal of the compressor bathed with oil. The shaft seal is
designed to work when it is coated with oil. If the seal is not
bathed with oil regularly, gravity will drain the oil from the seal,
and your freon goes bye-bye (or is that buy-buy?). A few minutes
every week, even during the winter months, will do.

Dave

--
Dave Carpenter

Whatever you wish for me,
May you have twice as much.