Partial A/C System Charge

Fig. 8 A/C System Charging:

Refer to Air Conditioning/Specifications/Capacitiesfor refrigerant capacities.

1. Prior to installing the manifold gauge set, close both manifold gauge set valves. Open the manifold gauge set needle valve.
2. Connect the left suction gauge test hose to the suction service port of the compressor, then the right discharge gauge test hose to the discharge service port.
3. Connect one end of the charging hose to the center manifold valve and the other end to the refrigerant dispensing manifold.
4. Close two of the dispensing manifold valves and open remaining dispensing manifold valve.
5. Attach a can of R-12 to the opened manifold valve. Ensure gasket is in place and in good condition. Tighten refrigerant can and manifold locking nut to ensure a good seal. Do not overtighten.
6. Turn dispensing manifold valve completely clockwise to puncture the can. This closes the valve and seals the refrigerant can.
7. Place the refrigerant can in a large pan of water heated to 125°F. Place pan of water containing the refrigerant can on an accurate scale so the amount of refrigerant added can be weighed. Open the refrigerant dispensing refrigerant manifold valve.
8. Purge all air from hoses. Air in the system will be trapped in the condenser causing abnormally high discharge pressures and interfere with condensing of the refrigerant.
9. Loosen both hoses at the manifold gauge set. Tighten hoses as soon as the air is purged.
10. Loosen charging hose connection at gauge set manifold. This will purge air from the charging hose. Tighten connection as soon as air is purged.
11. Open vehicle windows, then run engine at 1300 RPM.
12. Set air conditioning controls on A/C and blower switch on high.
13. If necessary, block airflow to the condenser to maintain a discharge pressure of 225-250 psi.
14. Charge the system through the evaporator suction service port as follows:
a. Slowly open the left suction gauge valve. Meter flow of refrigerant by adjusting the suction gauge valve so the pressure registered at the left suction gauge does not exceed 50 PSIG. Keep refrigerant can upright.
b. Add refrigerant gas until there is no foam visible in sight glass. As soon as all foam clears, note the weight on the scale.
c. Watch the scale and add exactly 1/2 pound of refrigerant to the system. Close the left suction gauge valve. Too much refrigerant in the system can cause abnormally high discharge pressures. Care must be used so that the exact recommended amount of refrigerant is added after the foam clears in the sight glass.
15. Close dispensing manifold valve, then disconnect hoses from the vehicles air conditioning system. Install protective caps at service ports.