Haier Unitary smart series Service Manual page 186

10) Temperature cutoff protection- Wired controller shows
confirm the malfunction
according to the fault code list
Is outdoor four-way valve
in good condition during
heating cycle?
yes
Does four-way
valve work
properly?
yes
Is indoor unit
malfunction caused by
lack of refrigerant?
yes
Is heat exchange effect
adversely affected by heavy dust
in indoor and outdoor units?
yes
Are indoor sensors for
ambient temperature and
coil properly located?
yes
Is resistance of indoor
sensor correct?
yes
Replace indoor PCB
Does small relay coil
no
of four-way valve have
a voltage of 12V DC?
no
Replace four-way
valve
no
charge refrigerant
no
cleaning
no
Relocate
no
Replace sensor
a__
0D
yes
Relay is broken.
Replace PCB
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