Refrigerant Circuit, Discharging With Service Station
- The refrigerant circuit is to be discharged if parts of the refrigerant circuit are to be removed, if there is any doubt about the quantity of refrigerant in the circuit or if safety precautions so require.
- The work procedure is always to be performed as described in the operating instructions for the A/C service station.
- The procedure described here is for the A/C service station ROB 134APF.
Before filling the refrigerant circuit with refrigerant, it should be evacuated (vacuum) for 45 minutes on systems with 1 evaporator and 60 minutes on systems with 2 evaporators. Moisture is also extracted from the circuit.
Leaks may be found when evacuating the refrigerant circuit.
Evacuating
- Do not start the engine during the evacuation process or when there is a vacuum in the refrigerant circuit.
- The A/C compressor could be damaged if the engine is started when there is a vacuum in the refrigerant circuit.
- Only start the engine when the refrigerant circuit is filled.
There is a possibility of refrigerant oil being extracted from the refrigerant circuit together with the refrigerant. To ensure compressor lubrication, the refrigerant oil in the circuit must be topped up with fresh oil. Refer to Maintenance, Diagnosis .
On vehicles with an A/C compressor without a magnetic clutch (with A/C compressor regulator valve -N280-), the engine should run < 10 minutes with the refrigerant circuit empty and closed (the A/C compressor also runs continuously). Engine speed must not exceed 2000 RPM.
On vehicles equipped with an A/C compressor with A/C clutch, the engine must be started since the A/C Pressure Switch -F129- or High Pressure Sensor -G65- (checks whether refrigerant is present in the circuit) switches off the A/C clutch as soon as there is no refrigerant in the refrigerant circuit.
-- Switch off the ignition.
-- Check refrigerant oil quantity in refrigerant circuit if necessary. Refer to Maintenance, Diagnosis .
-- Connect service station to power supply.
-- Check quantity of refrigerant in the A/C service station.
-- Connect charging hose of A/C service station to vehicle refrigerant circuit with quick-release coupling adapter (refer to vehicle-specific refrigerant circuit). Refer to [For engine(s) BLV, CCTA, CBFA] Description and Operation .
-- Only tighten the handwheel on the quick-release coupling adapter just enough so the valves in the service connections are securely open. Do not put too much pressure on the valve.
If pressure is to be measured after charging system on vehicles with a service connection on one side of the refrigerant circuit only, use valve adapter and charging hose with valve opener.
-- Initiate vacuum phase on the A/C service station. The refrigerant circuit is automatically evacuated. Check the preset evacuating time if necessary.
When the vacuum phase ends, the refrigerant circuit leak test begins. Pressure in bar and seconds are displayed.
Proceed as follows if the vacuum is not maintained:
-- Start the vacuum phase on the A/C service station again. The refrigerant circuit is automatically evacuated. Check the preset evacuating time if necessary. Watch the vacuum indicator for an extended period of time. Only when the vacuum is maintained can the refrigerant circuit be charged.
- If there is a leak that allowed enough air to enter during evacuation that the A/C service station cannot generate a sufficient vacuum or that the vacuum is lost immediately after switching the A/C service station off:
-- Determine the location of the leak in the refrigerant circuit as follows, refer to LEAK DETECTION .