You're right... I should've stated that it was 105 degrees inside my
workshop at the time.

I do like to push to 250psi, the system seems to cool much better with the
higher pressure and I haven't had any problems with blowing lines or
compressors... yet.

On my personal cars, I bite the bullet on stick with R-12.  Much, much
better cooling.

Cheers,

Jeff

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM]On Behalf
Of TJ Hannink
Sent: Thursday, June 05, 2003 12:02 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Converting to R134

--- Jeffrey Schwaia <jeff@TSSGI.COM> wrote:
> -Add freon till the high side reads ~250psi with the
> A/C on and the engine
> running at ~2000RPM.  Low side pressure should be
> ~35psi.

Down here in Florida, I look for no more than 200-psi
high side when the ambient temp is between 85-90F, the
vehicle is idling and in the shade. High side pressure
is directly related to the ambient temperature and
there are charts that will give you a direct
relationship, but as a rule of thumb, high side
pressure value should be around 2.2 times ambient
temperature (in F).

If you are going to look for 250psi on the high side,
I would advise installing an overpressure switch/valve
to keep from blowing out the compressor or the
fittings off the ends of the hoses when you get into a
hotter environment then where you were taking
measurements.

The '86+ vans A/C refrigerant high pressure switch
will switch the radiator fan to a higher speed when
the high side pressure goes over 210 psi. Above 95F,
mine runs constantly on the higher speed until the van
interior cools off.

I would also suggest replacing the engine cover and
closing the rear hatch to avoid sucking engine-heated
air into the evaporator when you do your pressure and
evaporator temperature readings.

> BTW & IMHO, the downside to R-134 (other than its
> inferior cooling ability)
> is the amount of power it robs from the engine when
> compare to R-12.  An
> R-12 system operates at a lower pressure than the
> R-134 system, which means
> the engine does not have to work as hard to turn the
> compressor.  The vans
> I've converted had a noticeably less power with
> R-134 than they had with
> R-12.  Perhaps it's just me...

No, I have noticed the same lack of power as well as a
1-2 mpg decrease in gas mileage when I am using A/C
every day, all day.

=====
TJ Hannink
Goldibox - 1987 Vanagon Camper, Wolfsburg Edition
Winter Park, Florida
http://home.earthlink.net/~tjhannink/
http://groups.yahoo.com/group/wolfsburg_campers
http://photos.yahoo.com/tjhannink [Vanagon] Album

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