26
Compressor Operation in Cooling
Mode:
In cooling mode, the maximum operation frequency (Fmax) of the
compressor, after it starts running, depends on the outdoor ambient
temperature (T4).
Onc e t he sys t em star t s runni ng, the compre s sor will r un at the Fmax
frequency for 7 minut es at a spec ific T4. During this time , the
frequency limitation is active, therefore the compressor will continue
running even if the s et point condition is satisfied. The compressor
running fre quency wil l then be controlled ba sed on the difference
betwe en the room tem perat ur e and the te m perat ur e set point (T1- Ts ) .
Outdoor Fan Operation in Cooling
Mode:
When in cooling mode, the outdoor fan motor cycles based on the
outdoor ambient temperature as shown below:
72
68
High
Low
°F
Fig. 27 – Outdoor Fan Motor Cycles
Indoor Fan Operation in Cooling
Mode:
When in cooling mode, the indoor fan runs continuously either at
the chosen set speed (high, medium, or low), or in Auto mode,
where the speed is determined by the microprocessor based on the
difference between the room temperature and the temperature set
point as shown below:
Fig. 28 – Indoor Fan Operation
HEATING MODE
In this mode, the system heats the room air with the indoor fan
running at either the selected speed or on Auto. As in the cooling
mode, the indoor fan will run continuously unless interrupted by
the cold blow algorithm. This algorithm will not allow the fan to
run if the indoor coil temperature drops below a preset value.
Defrost is controlled by the on - board microprocessor.
Compressor Operation in Heating
Mode
In heating mode, the maximum operation frequency (Fmax) of the
compressor, after it starts running, depends on the outdoor ambient
temperature (T4).
Once the system starts running, the compressor will run at the
Fmax frequency for 7 minutes at a specific outdoor ambient
temperature (T4). During this time, the frequency limitation is
active, therefore the compressor will continue running even if the
set point condition is satisfied. The compressor running frequency
will then be controlled based on the difference between the room
temperature, the temperature set point, and a temperature difference
that takes a default value of 32_F(T1-Ts-ΔT).
Outdoor Fan Operation in Heating
Mode
When in heating mode, the outdoor fan motor cycles based on the
outdoor ambient temperature as shown below:
63
59
Low
High
°F
Fig. 29 – Indoor Fan Motor Cycles
Indoor Fan Operation in Heating
Mode
In heating mode, the indoor fan runs depending on the evaporator
coil temperature (T2).
If the set point conditions are satisfied and the compressor stops,
the indoor fan will be forced to run for 127 seconds with breeze.
During this period, the anti- cold- wind is disabled.
If the m achine is r unning at the rate d c apa city test mode, the i ndoor
fan wil l run at the rated spee d and the anti- cold- wind function is
disa bl ed.
Auto Mode in Heating
Mode
In heating mode, when the fan speed is set to Auto, the fan will run
at a speed determined by the microprocessor based on the
difference between the room temperature and the temperature set
point as shown below:
Fig.30–AutoMode
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