31
Defrost Process
You may force a defrost in heat mode by pressing the “+” and “-” buttons alternately three times within 5
seconds.
1) e unit will enter defrost when the following conditions are met:
A. Outdoor ambient <= 41 F
B. Compressor had accumulated more than 3 hours of operation in heating mode
C. e outdoor coil <= 32 F
Note: e compressor runtime will be cleared when the outdoor ambient is > 41 F or when the compressor has started
up aer changing to cooling or drying mode and defrost has nished. e runtime will not be cleared when the unit has
stopped aer reaching the setpoint temperature, a protection fault or changing to fan mode.
ere are 3 perimeters used in the defrost algorithms, Outdoor ambient(T
outdoor
ambient), Outdoor tube(T
outdoor
tube) and
a calculated T
compensation
T
compensation
is calculated by the following:
D. Aer power-up, for the rst defrost T
compensation = 32
F
E. T
outdoor
tube > 36 F then T
compensation = 32
F
F. T
outdoor
tube <= 36 F then T
compensation = 37
F
2) When heating has operated continuously for 45 minutes, or accumulated for 90 minutes, the unit will enter defrost
mode in 3 minutes aer meeting any of the conditions below:
A. Outdoor ambient >= 41 F and outdoor coil <= 28 F
B. 28 F <= T
outdoor
ambient< 41 F, T
outdoor
tube <= 21 F
C. 23 F <= T
outdoor
ambient < 28 F <= T
outdoor
tube <= 18 F
D. 14 F <= T
outdoor
ambient < 23 F , T
outdoor
tube -T
compensation
<= (T
outdoor
ambient - 37 F)
3) During defrost, if run time for the compressor does not reach 3 minutes, the defrost cycle will not start for the next 2
hours. At that time the compressor stops operation and 30 seconds later the outdoor fan will stop. 30 seconds aer this the
4-way reversing valves will de-energized. Following another 30 second delay, the compressor will increase its compressor
speed for defrosting. Defrosting will last for 450 seconds or until the T
outdoor
tube >= 50 F, at this temperature the compres-
sor will decrease it compressor speed for 30 seconds, then will stop. In another 30 seconds the 4-way valve will energize,
the 60 seconds later the compressor and outdoor fan will start. e compressor speed for defrosting will be 85hz.
During Defrost mode, a “H1” will be displayed on the indoor front panel display indicating the user selected mode has
been overridden and the system is performing a outdoor coil defrost operation.
4) Defrost Sequence:
When a defrost condition has been met, the compressor will stop, all expansions valves will open fully, the outdoor fan will
stop 40 seconds aer the compressor stops. e 4-way valve will reverse direction (cooling mode) , then the compressor
will start and enter the defrost frequency. e control, board along with ambient sensors will calculate defrost time.
5) Oil Return:
Oil return condition can be met if the unit operates at a low frequency for an extended time. e indoor display will indi-
cate “H1” for this condition and is a normal procedure.
Product Introduction
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