GEA FK40/390 K Maintenance Manual page 13

6 I Fault diagnosis
Refrigerant temperature too high
Problem
Suction gas temperature
too high
Discharge pipe temperature
too high
Oil problems
Problem
Oil pressure too low
Oil foams during start-up phase
Oil foams during operating
Oil level decreases
Possible cause
- Suction gas overheating
- Too little refrigerant filling
- Liquid filter blocked
- Shortage of refrigerant
- Suction gas temperature too high
(Condensing pressure too high)
- Operating limits of compressor exceeded
- Cooling insufficient
- Short circuit between the discharge and the
suction side of the compressor
- Valve plate damage
- Internal decompression valve has opened
Possible cause
- Refrigerant in oil
- Too little oil in compressor
- Oil filter dirty / blocked
- Liquid refrigerant has moved into the oil sump - Check the laying of pipes
- Expansion valve not functioning
- During start-up, a portion of the oil is carried
to the refrigeration plant with the refrigerant
- Refrigerant in oil
- Piston rings worn
- Suction / discharge laminations of the valve
plate leaking
Remedy
- Adjust expansion valve
Insulate the gas suction line
- Establish the operating filling (see Operating
Instruction for the refrigeration plant),
localize leak
- Clean / replace filter / dryer
- Run leakage test / refill refrigerant
- Adjust expansion valve
Insulate the gas suction line
- see „Cutoff through high-pressure switch"
- see „Cutoff through heat-protection
thermostat"
- Check refrigerant filling
- Adjust expansion valve
- Check gaskets on valve plate /
change
- Replace valve plate
- Replace decompression valve (see the section-
on Disassembly / Assembly of Compressor)
Remedy
- see „Oil foams"
- Add oil and search for the cause of oil loss
- Clean / replace oil filter
Change oil
- Installation of the check valve in the
discharge line
- Installation of the solenoid valve in the
liquid line
- Check the control
- Adjust / replace expansion valve
- Refrigerant and oil get mixed. After some time
the oil level should stabilize.
Add oil, if necessary.
- see „Oil foams during start-up phase"
- Replace piston rings
- Replace valve plate
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