Gree TERRA09HP230V1A Installation, Service & Troubleshooting page 31

System Operation 18,000/24,000 btuh Models, cont.
Basic Functions
Heating Process, cont.
Defrost Process and Oil Return
1) The unit will enter defrost when the following conditions are met:
A. Outdoor ambient <= 410 F
B. Compressor had accumulated more than 3 hours of operation in heating mode
C. The outdoor coil <= 320 F
Note: The compressor run time will be cleared when the outdoor ambient is > 410 F or when the compressor has started
up after changing to cooling or drying mode and defrost has finished. The run time will not be cleared when the unit has
stopped after reaching the setpoint temperature, a protection fault or changing to fan mode.
There are 3 perimeters used in the defrost algorithms, Outdoor ambient(T
a calculated T
compensation
T is calculated by the following:
compensation
A. After energization, for the first defrost T
B. T tube > 360 F then T
outdoor
C. T tube <= 360 F then T
outdoor
Product Introduction
+90 F
+ 20 F
(Indoor display will indicate "H1", this is not a fault code)
= 32 0 F
compensation
= 32 0 F
compensation
= 37 0 F
compensation
Stop heating
ambient), Outdoor tube(T
outdoor
tube) and
outdoor
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