Gree U-MATCH Series Service Manual page 92

 F3 Malfunction of Outdoor Ambient Temperature Sensor
 F4 Malfunction of Discharge Temperature Sensor
Malfunction of
outdoor ambient
temperature
sensor
Check
if the outdoor ambient
temperature sensor on mainboard
is inserted on the needle stand
correctly
Yes
Disconnect
the temperature sensor and
measure if its resistance is
normal
Yes
Replace the
outdoor
mainboard
Malfunction of
discharge
temperature
sensor
Check if the
discharge temperature sensor on
mainboard is inserted on the
needle stand correctly
Yes
Disconnect
the temperature sensor and
measure if its resistance is
normal
Yes
Replace the
outdoor
mainboard
U-Match Series DC Inverter Service Manual
Correctly insert the
No
temperature sensor on
the needle stand
No
Replace the
temperature sensor
Correctly insert the
No
temperature sensor
on the needle stand
No
temperature sensor
89
Replace the