Date: Mon, 26 May 2003 18:28:44 -0400
Reply-To: lauterba <lauterba@BELLSOUTH.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: lauterba <lauterba@BELLSOUTH.NET>
Subject: Re: A/C Success (long)
Content-Type: text/plain; charset="iso-8859-1"
Ben, from your questions, it appears that you may not have had training in
dealing with system under pressure or vacuum. Such systems can be hazardous
to your health if you don't know what you are doing and are not wearing the
proper safety equipment. Likewise, the refrigerants themselves are toxic
and you should have training in the use of these substances before using
them (note: I do toxicology for a living).
I learned my A/C from watching some truly great craftspeople make and
install refrigeration and HVAC systems in the labs that I have managed over
the years. Likewise, I have had more than my share of experiences with high
pressure and high vacuum lab equipment (mass spectrometers, in particular).
Last summer the A/C on my vacation failed as water vapor had gotten into the
system through some leaky Schrader valves. Since I had used Freeze-12, none
of the local automotive A/C shops wanted to take my money to fix the system.
I went out and purchased my own vacuum pump. It is a two-stage direct drive
rotary pump from www.bestech.com . Yes, it was the better part of $300, but
if nothing else, my Son will need it when he gets old enough for science
fairs. I got the refrigerant and receiver-drier from list vendors. The
other stuff I needed, including the gauge set, I got from Pep Boys,
AutoZone, and my local Ace Hardware.
The system was already at atmospheric pressure when I took the old Schrader
valves out. Before pulling the old receiver-drier, I had experimented with
various ways of getting a vacuum on the system, and decided that the hose
that came with the gauge set was not going to cut it. The local Ace
hardware fixed me up with the necessary copper tubing, flare fittings, and
flared the tubing for me. I then made another practice run at pumping the
system down. I also knew from the sound of the vacuum pump that this was
not going to be a quick process.
After making sure that I could pump the system down, I changed the
receiver-drier. I did not clamp it back to the frame as I wanted to be able
to see the sight glass. I then pumped the system down through the
low-pressure side of the gauge set and the suction-side Schrader valve. It
would have been nice to have a decent vacuum gauge, but I had only the sound
of the vacuum pump as a guide (the gauge set was reading about -28 to -29
inches Hg so it was not useful) to the fact that the system was reasonably
leak free.
By this time, it was getting too late to charge the system. I let it pump
down overnight and it was into the afternoon before I had a chance to work
with it. I know that some will say an overnight pump down is too long;
however, I have pumped down enough mass spectrometers to know that it takes
overnight to get the most of the water out.
When I refilled the system, I used some of the refrigerant to purge the
lines of the gauge set before connecting it to the system. I stopped adding
refrigerant after I had added 3 pounds as I was getting more than adequate
cooling. I took the van out again this afternoon to make sure system was
still working well. I took about 30 minutes of highway driving to get
discharge air down to 45 deg. F (ambient was about 82 deg. F). Another 15
minutes of highway driving brought it close to 40 deg F.
John
----- Original Message -----
From: "Benjamin E. Beasley" <bbeasley@MIX.WVU.EDU>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Monday, May 26, 2003 7:33 AM
Subject: Re: A/C Success
> John,
>
> I am fascinated by your success story. I have a new receiver/dryer, a
R134
> conversion kit from Bus Depot and a gauge + R134 refrigerant system from
> Wal-Mart but haven't mustered up the nerve to try the swap. A few
> questions: Did you have the R12 evacuated by an A/C shop? What do you
mean
> by "I pumped the system down overnight"? Did you simply unbolt the old
> dryer and bolt in the new one then add coolant or do you have to have a
> vacuum drawn on the system first? Hopefully my swap goes as well as
yours.
>
> Ben Beasley
> '87 Vanagon GL Syncro "Babe, the big blue ox"
>
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM]On Behalf
> Of lauterba
> Sent: Sunday, May 25, 2003 9:58 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: A/C Success
>
>
> After installing the new receiver-drier, I pumped the system down
overnight
> and didn't get a chance to put the new refrigerant in until this
afternoon.
> I put in about three pounds taking care to purge the lines of my gauge set
> before hooking it to the system. The air from the A/C started cooling
down
> nicely so I stopped there even though there appeared to be pockets of gas
as
> the refrigerant passed under the sight glass of the receiver-drier. I put
> the clamp, which holds the receiver-drier to the frame, back on and gave
it
> a test drive. Ambient temperature was about 85 deg. F under hazy sun and
I
> had lots of air coming in through the heater vent. Still, the discharge
air
> from A/C quickly fell into the 50s. After about fifteen miles, I came
back
> home, pulled the grill, and put duct tape over the air entrance to the
> heater. I also sprayed some cleaner at the cooling coil to wash away some
> dirt. I then took the van out along US 41 at 50 to 60 mph, and the
> discharge air temperature stabilized around 45 deg. F.
>
> I am sure I did plenty of things wrong from not replacing the O-rings on
the
> receiver-drier to not adding enough refrigerant. However, "professional"
> A/C guys haven't done as well.
>
> John Lauterbach
> Macon, GA
> '84 7-passenger
>
| 
