27
Defrost
Defrost on heat pump units is controlled by the microprocessor and
is initiated if either of the following conditions occur:
1 If the outdoor temperature, T4>32_F0_C):
— The outdoor c oi l t e m perature ( T3) ha s bee n lower tha n
37F(3) for about 40 minut es. Duri ng that ti m e, the coil
tempe r ature is lower tha n TCDI for more tha n 3 minutes.
2 If the outdoor temperature, T4＜32_F0_C):
— If the conditions described above are met, the program
judges if the evaporator coil temperature (T2) has
decreased more than 41F(5). When the evaporator
coil temperature has decreased more than 41F(5), the
defrost mode starts.
3 At any value of outdoor ambient temperature (T4):
— If the mac hine runs wit h a condenser coil tempe r ature low er
than 37F(3) for more than 120 mi nute s and the outdoor
coil temperature (T3) has been lower than (TCDI+39F) for
mor e tha n 3 minutes, the machine ent ers the def rost mode.
Where: TCDI = - - 7C = 19.4F
Indoor fan running
rules
Indoor fan speed can be set as high, medium, low, silent mode or
auto grade. During all the fan speeds, the anti- cold- wind function
is preferential. If the compressor stops caused by the room
temperature rising, the indoor fan will run at super breeze. When
the compressor is running, the indoor fan is controlled.
Outdoor fan running
rules
In cooling mode the outdoor fan runs according to Fig 31.
Fig. 31 – Outdoor fan running rules
Condition of
defrosting:
----T4<32_F(0_C),
When the unit is running and the following two items are satisfied,
the unit starts defrosting. The units run with T3<37.4_F(3_C) for
40 minutes and T3 keeps lower than TCDI_Fformorethan3
minutes. The units run with T3<37.4_F(3_C) for 80 minutes and
T3 keeps lower than TCDI 35.6_F(2_C) for more than 3 minutes.
---- T4<32_F(0_C).
If the 1st condition and 2nd condition items are satisfied, then the
program judges if T2 has decreased more than 41_F(2_C). When
T2 has decreased more than 41_F(2_C) enter the defrosting mode.
No matter what value T4 is, if the machine runs with T3
<37. 4_F( 3_C) for more tha n 120 mi nutes and T3 keeps lowe r than
TCDI+ 39. 2_F(4_C) for more t ha n 3 minut es, the mac hine wil l enter
defrosting mode no ma tter if T2 drops more than 41_F( 5_C) or not.
Condition of ending
defrosting:
If any one of the following items is satisfied, the defrosting will
finish and the machine will turn to normal heating mode.
----T3risestobehigherthan TCDE 1_F
----T3keepsto behigherthanTCDE4_F for 80 seconds.
----Themachinehasrun for10 minutesindefrosting mode.
Defrosting
action:
Fig. 32 – 9k,12k, 18k, 24k, 30k models
XX=60s
Fig. 33 – 9k,12k, 18k, 24k, 30k models
Evaporator coil temperature
protection
----T2> TEH2_F, the compressor running frequency decreases to
the lower level and runs for 20s. When the frequency decreases to
F2 and the T2 is still over TEH 2_F for 3 minutes, the compressor
stops.
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