Refrigerant Circuit, Flushing With Refrigerant R134A: Flushing
-- Check refrigerant quantity in the refrigerant cylinder, there must be at least 15 lb (7 kg) of refrigerant R134a.
If necessary, switch on the heater installed on the refrigerant cylinder for 30 minutes before the first flushing procedure. This increases pressure in the refrigerant cylinder and accelerates charging of the flushing circuit.
-- Drain the old oil container of the A/C service station.
-- Connect the supply hose (high pressure side) of A/C service station to the low pressure line leading to the A/C compressor (line with larger diameter) using an adapter. Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT .
-- Connect return hose (low pressure- or intake side) of A/C service station to output of refrigerant circuit flushing device.
-- Connect the input on the refrigerant circuit flushing device to the high pressure line leading to the A/C compressor (line with smaller diameter) using an adapter. Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT .
Components are always flushed in the opposite direction of refrigerant flow when A/C system is in operation. Refer to FLUSHING CIRCUIT BLOCK DIAGRAMS .
While flushing, contaminants from the refrigerant circuit enter the refrigerant circuit flushing device and the A/C service station and are absorbed by the filters and dryers installed there. Depending on the contaminant, these components are to be replaced in shorter intervals in line with operating instructions for A/C service station or refrigerant circuit flushing device.
The filter in the refrigerant circuit flushing device depends on the type and degree of contamination in the flushed refrigerant circuit. It should be replaced after 2 flushing cycles, at the most. If a heavily contaminated refrigerant circuit is flushed (the refrigerant oil from the circuit is black and viscous or there are many shavings in the refrigerant circuit), the filter should be replaced after flushing. With a refrigerant circuit heavily contaminated in this way, it is wise to flush the circuit again after changing the filter.
Depending on the type of contamination, dirt (old refrigerant oil and abraded material from A/C compressor) is deposited on the viewing glass(es). Clean viewing glass(es) after flushing and flush the refrigerant circuit once more with one flushing procedure as a check.
Fluid refrigerant cannot be conducted with the necessary speed through the expansion valve, restrictor and desiccant bag of certain fluid reservoirs, therefore these components must be removed and replaced by an adapter. Refer to [For engine(s) BLV, CCTA, CBFA] Removal and Installation .
Adapters for connecting A/C service station and for bridging certain components of refrigerant circuit, refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT .
-- Switch on the service station and flush the refrigerant circuit (duration for one flushing cycle with three flushing procedures is approximately 1 to 1.5 hours for about 9 lb. (4kg) of coolant R134a).
Perform flushing of refrigerant circuit according to operating instructions of the A/C service station.
Depending on A/C service station version, the old oil container holds only approximately 125 cm 3 of refrigerant oil. In the event a system with a larger volume of refrigerant oil must be flushed, it may be necessary to empty the old oil container after the first flushing procedure of a flushing cycle.
Observe the refrigerant which flows back from the refrigerant circuit. The refrigerant circuit is only clean when the refrigerant flows clear and completely colorless through the viewing glass(es) on the flushing device in the A/C service station.
When flushing, the complete amount of refrigerant oil is washed out of the refrigerant circuit (except for minor remains which can be disregarded).
If contamination is especially severe, it may be necessary to perform the flushing cycle twice (two flushing cycles with three flushing operations each). Before the second flushing cycle, the filter on the flushing device must be replaced.