Outdoor Fan Starting Control In Cooling Or Dry Keep Mode - Daikin Sky Air R-407C Service Manual

Overview of the cooling mode functions
2.4

Outdoor Fan Starting Control in Cooling or Dry Keep Mode

1
Applicable units
2
Purpose
Unit specifications:
R35-45EZ7V11 and
RY35-45E(A)Z7V1
3
Method:
R35-45EZ7V11 and
RY35-45E(A)Z7V1
4
Method:
R(Y)P71-250B
5
Fan speed for
Ta < 3˚C:
R(Y)P71-250B
2–30
R(Y)P71-250B
R35-45EZ7V11
RY35-45E(A)Z7V1
The purpose is to avoid that the discharge pressure would start to rise, and stop the unit.
R35-45EZ7V11 has a mechanical thermostat.
RY35-45E(A)Z7V1 has an air thermistor and a low-high speed shift.
When the compressor starts, the fan keeps running at starting fan speed (no delay). The fan speed
depends on the ambient temperature. The different fan speeds for the according outdoor air
temperatures are shown in the table below.
Operating mode
Cooling mode, dry keep mode
When the compressor starts, the fan keeps running for 3 min at starting fan speed. The starting fan
speed depends on the ambient temperature. The different fan speeds for the according outdoor air
temperatures are shown in the table below.
Outdoor air temp.
Operating mode
Ta
Cooling mode, Ta < 3˚C
dry keep mode
3˚C ≤ Ta < 10˚C
10˚C ≤ Ta < 23˚C
Ta ≥ 23˚C
This fan starting control is made to be able to build up the compression ratio as soon as possible
because this has two advantages:
It is better for the compressor to increase the compression ratio because the lubrication must be
done by the pressure difference between low and high pressure.
The pressure difference is necessary for the h/p models to keep the 4-way valve in its correct
position.
Outdoor air temperature Ta
Ta > 20˚C
Ta < 17˚C
Starting fan speed
When the compressor is
ON for the first 20 s:
Fan speed = OFF
After 20 s:
Fan speed = L speed
L speed
H speed
HH speed
ESIE02–01
Starting fan speed
H speed
L speed
See further in this
section...
Fan speed for
Ta < 3˚C:
R(Y)P71-250B
Different fan speeds
Part 2 – Functional Description