|How to successfully recharge the A/C of the Porsche 911 that use rotary compressors such as SANDEN or similar and R134A gas.
The procedure is based on using the following equipment from Interdynamics, Brooklyn NY 11232.
1) Interdaynamics R-134a Service kit that comes with dispenser device and lowside pressure gauge.
2) A 12 oz can of R-134A/oil charge can (contains 2oz of oil)
3) A 12 oz can of R-134a charge can
4) A/C test thermometer
Primis charge cans can also be used (http://www.iqproducts.com)
A/C pressure reading check
1) Locate service low pressure service port on the compressor. The low pressure service port is usually identified by a blue cap. If it cannot be identified by the cap color, it can be identified by tracing the low pressure line that connects the evaporator to the compressor.
2) Start the engine and set A/C dashboard controls to max cooling.
3) Remove blue cap from service port. Connect the pressure gauge to the low pressure service port through the connecting hose. If the gauge reading is below 25 psi the A/C needs to be charged.
A/C charge procedure
4) Attach the dispensing device to the threaded area on top of the can containing the recharging gas.
5) Attach the dispensing device to the compressor's low pressure service port through the dispensing hose.
6) Hold the can in upright position and start opening the valve of the dispensing device.
7) When charging procedure is completed, close the valve of the dispensing device by turning the handle in clockwise position till stopped.
8) Remove charging valve and hose from can empty and discard.
After the charge procedure, the A/C should be checked again for the operative pressure (steps 1 to 3). If the operative pressure is not reached the A/C charge procedure should be repeated.
The A/C is fully loaded when:
1) The gauge reading shows a pressure between 25 and 45 psi.
2) The dryer shows the floating ball centered in the reading window.
A/C operative temperature check.
Place a thermometer on the main vent opening in the car dashboard. Turn on the A/C at max cooling.
After 5 minutes the thermometer reading should be between 45 and 60 F.
It is important to not overcharge the A./C system. Refrigerant should not be added when the gauge reading is more than 45 psi. The total capacity of the A/C is about 25 oz therefore no more than 2 cans should be used.
Pelican Technical Article:
911 AC Refrigerant Recharge and Maintenance
Porsche 911 (1965-89)