Lennox MMDB Service Manual

99
24.7. Outdoor Fan Control
24.7.1. Cooling Mode
Normally the system will choose the running fan speed according to ambient temperature:
T4
A DC_FAN_HI_SPD_ADD
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℃
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

Lennox MMDB Specifications

General

Brand	Lennox
Model	MMDB
Category	Air Conditioner
Language	English