Grundig GHP-MM08, Service Manual

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Heat Pump Monobloc Inverter / User Manual
202202 Heat Pump Space Heater 72
4.4.21 E20 E21Diagnosis and analysis
4.4.21.1 Diagnosis
Code E20 will occur when the compressor startup failed. When one or two phases are
missing from the compressor phase line U V and W, Code E21 will occur.
4.4.21.2 Possible causes
!
Too much liquid flooded into the compressor.
!
There is too high pressure difference between inlet and outlet of the compressor.
!
There is a wrong compressor phase sequence.
4.4.21.3 Analysis and action
Yes
NO
Yes
NO
NO
Yes
E20 E21
Ensure the amount of refrigerant is
correct
Too much liquid flooded into the
compressor?
Replace drive PCB
There is too high pressure difference
between inlet and outlet of the
compressor?
Ensure compressor inlet and outlet
pressures are equal before starting
the compressor
Compressor phase sequence is wrong or
missing?
Reconnect U V W terminals by the
correct phase sequence