6 | AX452438944357en-000301
© Danfoss | Climate Solutions | 2023.09
2 I Fault diagnosis
Compressor temperature too high
Problem
Possible cause
Remedy
Suction gas temperature
too high
- Suction gas overheating
- Adjust expansion valve
Insulate the gas suction line
- Too little refrigerant filling
- Establish the operating filling (see Operating
Instruction for the refrigeration plant)
Localize leak
- Liquid filter blocked
- Clean or replace filter / dryer
- Shortage of refrigerant
- Run leakage test
/ refill
refrigerant
Discharge pipe temperature
too high
- Suction gas temperature too high
(Condensing pressure too high)
- Adjust expansion valve
Insulate the gas suction line
- see „Cutoff through high-pressure switch“
- Operating limits of compressor exceeded
- see „Cutoff through heat-protection
thermostat“
- Cooling insufficient
- Check refrigerant filling
- Adjust expansion valve
- Short circuit between the discharge and the
suction side of the compressor
-
Check gaskets on valve plate /
change
- Valve plate damage
- Replace valve plate
- Internal safety valve has opened
- Replace safety valve (see chapter
disassembly / assembly of the compressor)
Oil problems
Problem
Possible cause
Remedy
Oil pressure too low
- Refrigerant in oil
- see „Oil foams“
- Too little oil in compressor
- Add oil and search for the cause of oil loss
- Oil filter dirty / blocked
- Clean / replace oil filter
Change oil
Oil foams during start-up phase
- Liquid refrigerant has moved into the oil sump - Check the laying of pipes
- Installation of the check valve in the
discharge line
- Installation of the solenoid valve in the
liquid line
- Check the control
Oil foams during operating
- Expansion valve not functioning
- Adjust / replace expansion valve
Oil level decreases
- During start-up, a portion of the oil is carried
to the refrigeration plant with the refrigerant
- Refrigerant and oil get mixed. After some time
the oil level should stabilize.
Add oil, if necessary.
- Refrigerant in oil
- see „Oil foams during start-up phase“
- Piston rings worn
- Replace piston rings
- Suction / discharge fins of the valve plate
leaking
- Replace valve plate
