Lennox MPB048S4M - Four-Way Valve Control

165
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.
38
Exit low ambient cooling
mode
, run with high fan
for 1 minute
Low
30
27
23
off
31.5.2. Heating Mode
Normallythesystemwillchoosetherunningfanspeedaccordingtoambienttemperature:
T4
E DC_FAN_SSLOW_SPD_ADD
D DC_FAN_SLOW_SPD_ADD
C DC_FAN_MIN_SPD_ADD
B DC_FAN_MID_SPD_ADD
A DC_FAN_HI_SPD_ADD
21℃
19℃
18℃
16℃
15℃
13℃
12℃
10℃
31.6. Four-Way Valve Control
Inheatingmode,four-wayvalveisopened.Indefrosting,four-wayvalveoperatesinaccordingtodefrostingaction.Inother
modes,four-wayvalveisclosed.Whentheheatingmodetoothermodes,thefour-wayvalveisoffaftercompressorisoff
for2minutes.Failureorprotection(notincludingdischargetemperatureprotection,highandlowpressureprotection),four-
wayvalveimmediatelyshutsdown.