Oil Recovery During Compressor Operation At Low Frequency; Outdoor Unit Fan Control - Mitsubishi Electric PURY-HP72 Service Handbook

[5-2 Outdoor Unit Control ]
5-2-10

Oil recovery during compressor operation at low frequency

Oil collection operation is performed after units have been operated continuously for an extended period at the compressor
frequency F as listed in the table below (Condition 1). It is performed by fixing the compressor frequency F to the value listed
below (Condition 2) for a maximum of four minutes.
The opening of the LEV on indoor units will increase during oil collection operation.
Condition 1
Condition 2
5-2-11

Outdoor Unit Fan Control

(1) Control method
Depending on the capacity required, the rotation speed of the outdoor unit fan is controlled by the inverter to keep a constant
condensing temperature of (outside temperature +10°C [50°F]) during cooling operation and a constant evaporation temper-
ature of (0°C [32°F] =0.71 <Pa [103psi]) during heating operation.
The OS in the multiple-outdoor-unit system operates at the actual outdoor unit fan control value that is calculated by the OS
based on the preliminary outdoor unit fan control value that the OC determines.
(2) Control
Outdoor unit fan stops while the compressor is stopped (except in the presence of input from snow sensor).
The fan operates at full speed for 5 seconds after start-up.(Only when TH7<0°C [32°F])
The outdoor unit fan stops during defrost operation.
(3) Outdoor unit heat exchanger capacity control patterns
Model
HP72, HP96 models
HWE13080
Compressor frequency (F)
HP72
F < 22
F = 25
Operation
Operation mode
patterns
Cooling-only 1
Cooling-main
2
3
Heating-only 1
Heating-main 1
2
Defrost 1
F = 36 (Cooling-Only and Cooling-Main)
F = 46 (Heating-Only and Heating-Main)
Solenoid valve
SV4a SV4b
OFF ON
OFF ON
ON ON
ON ON
ON ON
ON ON
ON ON
- 130 -
HP96
F < 32
SV4c SV4d
- ON
- OFF
- OFF
- OFF
- ON
- OFF
- OFF
GB