4 | AX452438944357en-000301
© Danfoss | Climate Solutions | 2023.09
Compressor stand still
Compressor does not start
Problem
Possible cause
Remedy
Control circuit is interrupted
Main - or control fuse is switched off or tripped
Replace fuse
Determine and remove the cause
Cut off through:
- Low pressure switch
- High pressure switch
- Heat protection thermostat
- Control thermostat
- Other safety elements
Locate the interruption in the circuit
and remove
Malfunction of electromagnetic
clutch
- see also p. 16 „Malfunction of
electromagnetic clutch“
Checking
Compressor cutoff
Compressor starts and stops again
Problem
Possible cause
Remedy
Low pressure switches off
Suction pressure too low:
- Check the setting of the low pressure switch
- Adjust the switching points or replace switch
- Suction valve of the compressor closed
- Open suction valve
- Capacity of compressor too large
- Check operating conditions
- Refrigerant deficiency
- Leak test / add refrigerant
- Filter / dryer in the liquid line blocked
- Replace filter / dryer
- Expansion valve not functioning properly
- Check the setting of the expansion valve
- Solenoid valve on the liquid line not opening
- Check the control / function
2 I Fault diagnosis
Fault diagnosis
In case of malfunctions during compressor operation we recommend
to prepare a measurement record for aiding the fault search:
Pressure measurement: Discharge side, suction side,
oil pressure
Temperature measurement: Compressor housing,
discharge end temperature, suction gas overheating
According to the expected cause of the fault it may be necessary
to check the electrical systems for faults in the control.
In order to localize the causes of operating malfunctions as easy
as possible we have compiled the following table with suggesti-
ons for remedying compressor malfunctions. Further information
is available on our failure analysis slide that can be downloaded
on www.bock.de.
Function faults - Symptoms
Function faults arising most frequently and their symptoms are:
Compressor stoppage, compressor cutoff
- Compressor does not start
- Compressor starts and then stops again
Refrigerant performance too low
Temperature of the compressor too high
Oil problems
Abnormal compressor running noise
