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JFairman JFairman is offline
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Join Date: Jul 2006
Location: S. Florida
Posts: 7,274
If you're using R12 it's easy... just add freon if there is already correct oil in the system until the bubbles go away on the sight glass in the reciever dryer.
Thats in the back edge of the left side front left wheel well.

If the system is totally stock and using stock diameter hoses and you're charging R12 from a 30lb bottle sitting on a scale, the weight of the proper R12 charge is on a sticker on the side of the air cleaner housing.

The regrigerant capacity and weight will probably be a little different between a 911 and 930 because the rear condensors are sized and shaped differently.

On a day in the mid eightees the pressures will be around 30 on the low side and 220 or so on the high side but thats a big generalization depending on temperatures.
Just clean the sight glass and watch it while adding freon until the bubbles go way with it running, rear engine lid down so air is drawn over the condensor. Stop immediately when the bubbles disappear.
You're better off and the air will be cooler a little under charged (but not alot) than over charged.

If using R134 the sight glass is useless and you have to go by pressures and temperatures and it changes non linear and quickly.
Someone already posted a link with help on those.
Old 07-12-2010, 12:15 PM
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