BOCK FK40 - Compressor Cutoff Troubleshooting

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09665-07.2021-Gb
6 I Fault diagnosis
Refrigerant performance too low
Problem Possible cause Remedy
Suction pressure too high
- Evaporator iced up - Remove the cause
- Expansion valve not functioning properly
- Check expansion valve setting;
replace valve, if necessary
- Lack of compressor capacity
- Check the function of the compressor by
evacuating to vacuum.
Check function of capacity regulator
(accessory)
- Shortage of refrigerant - Run leakage test / rell
refrigerant
Suction pressure too low
- See „Cutoff through low-pressure switch“ - Checking
High-pressure too high
- See „Cutoff through high-pressure switch“ - Checking
High-pressure too low
- Condenser being cooled to much - Adjust the control of condenser cooling
- Lack of compressor capacity
- Check compressor / Check the functioning
of capacity regulator
- Pressure laminations of valve plate leaking - Replace valve plate
- By-pass between suction and discharge side
- Localize leak between the discharge and suc-
tion side and repair it
Problem Possible cause Remedy
Cutoff through high pressure
switch
Condensing pressure too high:
- Check the setting of the high-pressure switch
- Adjust the switching points or replace switch
- Pressure valve of the compressor closed - Open the pressure valve
- Condenser fan not functioning - Check the control / replace motor
- Condenser performance insufcient, con-
denser and fan motor contaminated
- Cleaning of condenser ns and fan
- Excessive refrigerant lling - Extract refrigerant to normal lling
- Non-condensible gases in refrigerant - Extract refrigerant and evacuate the
refrigeration plant / rell refrigerant
Cutoff through heat protection
thermostat (accessory)
Discharge end temperatures is too high
- Operating limits of compressor exceeded
- Adapt the operating conditions
to the operating range
- Suction gas overheating - Check expansion valve / check
insulation on the suction side
- Condenser cooling insufcient
- Check fan motors / cleaning of condenser
- Valve plate damage - Replace valve plate
- Internal decompression valve has opened - Replace decompression valve
-> Check compressor and refrigeration plant
Determine and remove the cause for the
inadmissible high pressure in the high-
pressure side
Cutoff through control
thermostat
Temperature over / below the desired range Check operating points