How to Determine if your Audi is Actually Short of Refrigerant

[jlagnese at massed.net]

Checking the sight glass for bubbles is one way.
---- Original message ----

  Date: Wed, 2 Jul 2008 23:52:44 -0400
  From: <mboucher70 at hotmail.com>
  Subject: How to Determine if your Audi is Actually
  Short of  Refrigerant
  To: <quattro at audifans.com>
  >Short of taking a car to an AC shop, what is a
  good method to determine if
  >its actually short of refrigerant?
  >
  >Having discussed the possibilities for
  refrigerant top-up and all but
  >settled on Duracool from the nearest Wal-Mart, I
  thought I'd do a
  >thermometer test.
  >
  >The test was conducted on a cool day with
  temperature about 70F. I started
  >the car, set it to idle fast at about 1600rpm,
  turned the AC on max, and
  >mounted an aquarium thermometer in front of the
  vent. Somewhere around the
  >2or 3 minutes mark, the vent temperature was
  below 50F. After that, it
  >continued a slow climb downwards, eventually
  bottoming out at 42F, after
  >about 10minutes.
  >
  >One thing that surprised me slightly was the
  frequency of the compressor
  >cycling. The compressor appeared to cycle
  regularly at about 15 seconds.
  >I'm measuring the compressor cycling by the point
  at which the idle would
  >jump from a steady idle of 1600rpm to a steady
  idle of 2000rpm during the
  >test.
  >
  >I was a bit surprised that the temperature got
  down as low as 42F. I had
  >assumed that the system was low on refrigerant
  based on a very sunny hot day
  >last summer with 5 people in the car. On that
  day, despite constant max/AC
  >and max fan, the car just never got very cool.
  >
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