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09665-07.2021-Gb
6 I Fault diagnosis
Abnormal running noise from compressor
Problem Possible cause Remedy
Fixation of compressor is loose
- Screwed connections have become loose
- Securing elements for screwed connections
missing
- Tighten the screwed connections and secure
them anew
- Vibration metals defective - Replace vibrations metals
Liquid shock
- Liquid refrigerant reaching the compressor
- Adjust / check expansion valve
Check refrigerant lling
Check evaporator fan
- Icing-up of the evaporator
- Oil shocks because of too much oil - Check oil level
Check the dimensioning of pipes (gas velocity)
Replace worn piston rings
Capacity regulator (accessory)
- Switching on and off constantly / oscillating - Check the control
- Defective - Replace capacity regulator valve
Electromagnetic coupling slipping
- see also p. 14 „Malfunction of electromag-
netic coupling“
- Checking
V belt drive,
increased noise generation
- Belts vibrating excessively - Check belt tension
Use tensioning roller / guidance roller
- Incorrect alignment of compressor and motor - Check alignment and adjust anew
Malfunction of the electromagnetic coupling
Problem Possible cause Remedy
Coupling not switching
- No voltage applied - Apply voltage and check
Coupling slipping too long, get-
ting hot, smoking and squeaking
- Voltage too low - Keep the voltage at 12 or 24 Volts (check
vehicle network)
- Driving power too high - Check operating conditions
- Rotor rubbing at the magnetic eld - Check the seating of the magnet possibly
to high belt tension
Coupling not separating
- Voltage still being applied to the magnet - Check switch / relay
- Coupling is stuck - Disconnect the armature disc from the rotor
mechanically
- Coupling overloaded,
Armature disc is deformed
- Install new rotor ans armature disc
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