Lennox MCA Series - Outdoor Fan Control; Cooling Mode

30
OutdoorTemperature(T4)
Cooling
>29°C 18°Cto29°C <17°C
>84.2°F 64.4°Fto84.2°F <62.6°F
ModifyRate 100% 60% 40%
Whenthereismorethanoneindoorunit:
OutdoorTemperature(T4)
Cooling
>25°C 17°C-25°C <17°C
>77°F 62.6°F-77°F <62.6°F
ModifyRate 100% 80% 40%
NOTE: The nal result is integer.
Inlowambientcoolingmode,modifyrateisxedas40%.
Accordingtothenalcapacityrequesttoconrmheoperatingfrequency,asfollowingtable.
Frequency(Hz) 0
COOL_
F1
COOL_
F2
...
...
COOL_
15
COOL_
16
Amendatorycapacity
demand
0 1 2
...
...
15 16
Meanwhilethemaximumrunningfrequencywillbeadjustedaccordingtotheoutdoorambienttemp.
17.3. Outdoor Fan Control
17.3.1. Cooling Mode
Normallythesystemwillchoosetherunningfanspeedaccordingtoambienttemperature:
T4
A DC_FA N_HI_SPD_ADD
B DC_FA N_MID_SPD_ADD
C DC_FA N_MIN_SPD_ADD
D DC_FA N_SLOW_SPD_ADD
E DC_FA N_SSLOW_SPD_ADD
23℃
22℃
20℃
28℃
19℃
17℃
26℃
25℃
Whenlowambientcoolingisvalid:
27
High
Low
25
20
15
low ambient cooling
Outdoorfanspeedcontrollogical(lowambientcooling).
WhenT4<15°C(59°F)andT3<30°C(86°F),theunitwillenterintolowambientcoolingmode.Theoutdoorfanwillchoose
speedaccordingtoT3.
WhenT3≥38°C(100.4°F)orwhenT4≥20°C(68°F),theoutdoorfanwillchoosethespeedaccordingtoT4again.