Drainage of A/C System
WARNING:- Before commencing work, read and observe SAFETY PRECAUTIONS when working on A/C systems.
Technician Safety Information
- Always wear protective goggles and gloves when working with refrigerant Contact with eyes and skin may cause frostbite.
- Mixtures of R134a and compressed air must not be used for troubleshooting due to the risk of explosion at high pressures and temperatures.
CAUTION: Read General information on repair and replacement of A/C system components under A/C SYSTEM COMPONENTS. Vehicle Damage Warnings
NOTE:
- The A/C system in the car must be at least at roam temperature, approx. 2O °C (68 °F), to achieve fast drainage. In winter therefore the car should be housed overnight in the workshop before commencing work.
- The drainage time will be reduced if the A/C system has recently been in service and the engine is hot (radiation heat). If possible run the system for about 5 minutes before draining to shorten the time.
Draining Refrigerant From Car To RHS 650 Unit
1. Check gauge glass (22) to ensure that RHS 650 is not full of refrigerant but that capacity is available for at least another 1000 grammes (2.205 lb). If unit requires to be drained see DRAINAGE TO STORAGE CONTAINER (gas bottle).
Filling of Storage Container With Refrigerant From Unit
2. Connect RHS 650 to single-phase 220 V/5O Hz grounded supply.
3. Settings:
- Valves (1), (2), (3) and (4) must be closed. Connect low-pressure hose (blue) to high-pressure circuit (14).
- Connect high-pressure hose (red) till low-pressure circuit (13). Connection (20) should be closed.
- Set selector switch (7) to TEST.
4. Check that low-pressure hose (blue) connection fitting is closed i.e. turned counterclockwise to end position.
5. Connect low-pressure hose (17) (blue) to A/C system service valve in car.
NOTE: The A/C system service valve is located on the pipe beside the diagnostic units (DLCs). This applies to cars from 1994 on.
6. Open Schraeder valve on connection fitting by turning cock clockwise (OPEN) as illustrated.
7. Draining refrigerant:
- Close main switch (11).
- Set selector switch (7) to RECOVERY (drainage).
- Open valves (1) and (2) slowly (otherwise oil may escape from system).
- Unit will drain system automatically.
NOTE: If RHS 650 unit requires to be filled with R134a from an external gas bottle, low-pressure connection (13) should be used for this purpose. This may be carried out while the A/C system in the car is being drained through the high-pressure connection.
- The quantity of refrigerant drained may be read from the gauge glass (22) on the glass storage cylinder.
- If the unit becomes full, the red warning lamp (8) will light and the compressor will stop.
- The RECOVERY lamp (9) will light, indicating that the compressor is running, as long refrigerant remains in the system. The lamp will go out and the compressor will stop automatically when the system pressure is sufficiently low.
- The low-pressure gauge (12) should now indicate a partial pressure; in other words, a value below 0 bar (atmospheric pressure), normally -0.2 to -0.4 bar (2.9 to 5.8 psi). The pressure will return to 0 bar after approx. 5 minutes and will stabilize at that value. However, if the pressure remains low, the compressor will restart. The A/C system is now drained.
- The drainage procedure from starting of the compressor until the unit stops and the pressure returns to 0 normally takes 20-25 minutes.
8. Open main switch.
NOTE: The gauge glass (22) on the glass storage cylinder does not indicate the exact quantity of refrigerant drained from the A/C system since a certain amount always collects in the drainage unit air receiver.
Draining Refrigerant From Car To RHS 3000 Unit
1. Disconnect battery ground lead.
2. Before commencing work, check the oil level in the drainage unit compressor and vacuum pump.
3. Check for oil in the oil gauge glass (25). If oil is present, drain by opening oil drain cock (27).
4. Check that all cocks are closed.
5. Connect drainage unit to grounded, 220 V 50 Hz supply.
6. Connect to oil-free compressed air supply, max. pressure 10 bar (145 psi).
7. Close main switch. White indicating lamp should light.
8. Press RECOVERY/RECLAIM (4) push-button. Air receiver will be drained automatically and unit will then be ready for service.
9. Connect high-pressure hose (red) (18) to A/C AC system air receiver (28). Open cock (15) slowly.
- If system contains refrigerant, green lamp (8) will light, indicating that compressor is running. When system has been depressurized, lamp will go out and compressor will stop automatically. If pressure remains low, compressor will not restart. A/C system is then drained.
- Drainage normally takes 15-20 minutes.
NOTE: If the unit is to be used for diagnostic purposes, connect high-pressure hose (red) (18) to compressor high-pressure side and low pressure hose to compressor low-pressure side.
10. Check oil gauge glass (25) to see if oil from A/C system has been drained with refrigerant.
11. Drain off excess oil by opening oil drain cock (27).
- Measure oil quantity and till compressor with same quantity of oil before charging A/C system with refrigerant.
- Refrigerant level can be read from glass cylinder gauge glass (20). If unit becomes full 4.5 kg (9.921 lb), red warning lamp will light and compressor will stop.