Mitsubishi Electric PUHY-HP72 Service Handbook page 98

[5-2 Outdoor Unit Control ]
Operation
When Continuous heating
mode
HWE18240_GB
ON
Front part of heat exchanger is being de-
frosted.
SV10
OFF
Other than on the left
When the rear part of heat exchanger is
being defrosted, 21S4b will be OFF.
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