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Only for training and service purposes
Part 2 Functions & Controls
5.12 Low Ambient control
5.12.1 9,12kBtu/h Model
• If outdoor temperature drops below a certain temperature, liquid return is prevented by On/Off control of outdoor fan.
• It can prevent frosting of evaporator and keep cooling operation
5.12.2 18, 24, 30kBtu/h Model
Low ambient cooling case : In this situation outdoor fan works in ON/OFF control.
: If the pipe temperature 0°C(32°F) and it is falling rapidly, the compressor will run for 5 min & then it will go into
low ambient control. (❈ Temp. value can be different for each model.)
❈ After the system is stopped by CT cut or heat sink cut-off then the cycle returns to the normal conditioned con-
trol.
(T1 = 0)°C
(T2 = 0)°C
Outdoor pipe temp
O/D fan
Set speed
Off
Off
Set speed Set speed
Model
Mode-in by outdoor
pipe temp.
Mode-in by indoor
pipe temp.
Outdoor fan-on time ≥ 3 min.
(And) Outdoor pipe temp. ≤ 4˚C (39˚F)
(And) Outdoor temp. < 10˚C (50˚F)
Comp-on time ≥ 5 min.
(And) Indoor pipe temp. ≤ 4˚C (39˚F)
(And) Outdoor temp. < 10˚C (50˚F)
Outdoor fan-off time ≥ 5 min.
(Or) Outdoor pipe temp. ≤ 20˚C(68˚F)
(And) Outdoor temp. ≥ 10˚C (50˚F)
Outdoor fan-off time ≥ 5 min.
(Or) Indoor pipe temp.≤ 4˚C (39˚F)
(And) Outdoor temp. ≥ 10˚C (50˚F)
Mode-in Condition
Mode-out Condition
Model T1 [˚C(˚F)] T2 [˚C(˚F)]
18kBtu/h 18(64) 18
24kBtu/h 16(61) 16
30kBtu/h 0(32) 0