Lennox MPB036S4M-*P - Defrost Termination; Outdoor Fan Control

164
Compressor
4-Way valve
Outdoor fan
10S
10S
X2
X1
31.4. Defrost Termination
Defrostwillterminateif:
T2isgreaterthan64.4°F.
T3isbetween64.4°Fand43.4°Ffor80seconds.
Systemhasbeenindefrostfor10minutes.
0
10
15
29 < 30
35
40
2 Hours
Run-time count starts
T3 time
mea-
sured
and T3
temp
deter-
mined
14 minutes
6 min
5 min
After first 15 minutes of
operation, if T3 <
19.4°F then defrost,
otherwise monitor T3
for next 14 minutes.
After 36 minutes of
run-time T3 < 23°F and
T3+5.4°F is still less than
or equal to T30.
2 hours have passed
and T3 < 5°F.
This formula depends on humidy. The higher the humidity, the more frequent the defrost cycles. With no humidity, there
will be less frost build-up. Defrost is a function of humidity.
After 29 min-
utes of run-time
T3 < 19.4°F
and T3+5.4°F is
still less than or
equal to T30.
After 40 minutes of run-time
T3 < 11.2°F.
31.5. Outdoor Fan Control
31.5.1. Cooling Mode
Normallythesystemwillchoosetherunningfanspeedaccordingtoambienttemperature:
T4
A DC_FAN_HI_SPD_AD D
B DC_FAN_MID_SPD_ADD
C DC_FAN_MIN_SPD_ADD
D DC_FAN_SLOW_SPD_ADD
E DC_FAN_SSLOW_SPD_ADD
23℃
22℃
20℃
28℃
19℃
17℃
26℃
25℃