64 51 Leak-Testing Evaporator
It is essential, when handling nitrogen, to observe the standard national safety regulations.
Ensure that employees are advised of how to handle pressurized vessels and nitrogen correctly (danger of asphyxiation). For this purpose, follow the notes and instructions in the technical safety specifications available from the gas supplier.
Necessary preliminary tasks:
- Remove expansion valve
Replace sealing rings. Use special tool 00 9 030 to mount sealing rings without damaging them.
Connect special tool 64 5 126 to retaining clip and screws of expansion valve. Tightening torque 64 53 9AZ . Connect special tool 64 5 121 to special tool 64 5 126 .
Pressurize evaporator to 10 bar slowly only. Excessively fast pressurization and pressures in excess of 20 bar may cause damage to the evaporator.
Connect nitrogen pressure bottle with pressure reducer to pressure gauge and then connect to special tool 64 5 121 (connecting hose).
- Testing apparatus must be leakproof.
- Ambient temperature and temperature of vehicle must not change during the test procedure.
- Do not move the vehicle during this period
Apply test pressure of 10 bar slowly and close nitrogen pressure bottle.
Check leak-tightness of testing apparatus and of connection to refrigerant line.
Set test pressure of 10 bar is only permitted to drop by 2 bar to 8.5 bar over a test period of 1.5 hours.
If the pressure loss is greater than 1.5 bar, this indicates that there is a leak in the evaporator unit.
After leak-testing:
- Replace sealing rings. Use special tool 00 9 030 to mount sealing rings without damaging them.