Service manual

ESIE03–01 Overview of the cooling mode functions
Part 2 – Functional Description 2–35
3
2
4
5
1
2.5 Normal Outdoor Fan Control in Cooling Operation
Applicable units R(Y)P71-125L
Purpose The purpose of this normal outdoor fan control is to ensure a correct discharge pressure in function of
the outdoor air and indoor room temperature.
Method The table below shows in which conditions the outdoor fan works at low or high speed.
Ta = ambient temperature = outdoor air temperature; Tr = room suction temperature; Tc = condensing
temperature (overload control)
Different fan
speeds
The table below explains the meaning of L, H and HH fan speed.
Used input The normal outdoor fan control during cooling operation uses the following inputs:
Low outside
temperature control
(Year round
cooling)
The purpose of this control is to prevent freezing of the indoor heat exchanger due to a low pressure
drop by reducing the air flow volume of the outdoor unit fan.
The control is activated when the outdoor temperature drops below (41.7 - 0.84 x Tr).
At this temperature, the outdoor fan speed switches to L-tap.
The differential for the return is 4°K.
The control is not activated during start-up control.
Condition Fan Speed
Ta < -7°C OFF
Ta < 41.7 - 0.84 x Tr L speed
Ta > 45.7 - 0.84 x Tr H speed
Tc > 58°C HH speed
Fan operation
71 100 and 125 200 and 250
1 fan
Upper fan
(MF1)
Lower fan
(MF2)
Fan 1 Fan 2
OFF OFF OFF OFF OFF OFF
L LLLHOFF
H HHHHH
HH HH HH HH H H
Input
Connection on
indoor PCB
Connection on
outdoor PCB
Indoor room temperature R1T X19A —
Outdoor air temperature R1T — X4A