Outdoor Fan Control; Liquid Compression Protection Function; Defrost Control - Daikin 4MXL-T Series Service Manual

Control Specification
4.9

Outdoor Fan Control

1. Fan OFF control during defrosting
2. Fan OFF delay when stopped
3. Fan speed control for pressure difference upkeep
4. Fan control when the number of heating room decreases
5. Fan speed control during forced cooling operation
6. Fan speed control for POWERFUL operation
7. Fan speed control during indoor/outdoor unit quiet operation
8. Fan ON/OFF control when operation (cooling, heating, dry) starts/stops

4.10 Liquid Compression Protection Function

Outline
The compressor stops according to the outdoor temperature for protection.
Details Operation stops depending on the outdoor temperature.
The compressor turns off under the conditions that the system is in cooling operation and the
outdoor temperature is below –12°C (10.4°F).

4.11 Defrost Control

Outline
Defrosting is carried out by the cooling cycle (reverse cycle). The defrosting time or outdoor heat
exchanger temperature must be more than a certain value to finish defrosting.
Details
Conditions for Starting Defrost
 The starting conditions are determined with the outdoor temperature and the outdoor heat
 The system is in heating operation.
 The compressor operates for 6 minutes.
 More than A minutes of accumulated time have passed after the start of the operation, or
Conditions for Canceling Defrost
The judgment is made with the outdoor heat exchanger temperature. (B°C (C°F))
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The outdoor fan is turned OFF while defrosting.
The outdoor fan is turned OFF 60 seconds after the compressor stops.
The rotation speed of the outdoor fan is controlled for keeping the pressure difference during
cooling operation with low outdoor temperature.
 When the pressure difference is low, the rotation speed of the outdoor fan is reduced.
 When the pressure difference is high, the rotation speed of the outdoor fan is controlled as
well as normal operation.
When the outdoor temperature is more than 10°C (50°F), the fan is turned off for 30 seconds.
The outdoor fan is controlled as well as normal operation during forced cooling operation.
The rotation speed of the outdoor fan is increased during POWERFUL operation.
The rotation speed of the outdoor fan is reduced by the command of the indoor/outdoor unit
quiet operation.
The outdoor fan is turned ON when the operation starts. The outdoor fan is turned OFF when
the operation stops.
exchanger temperature.
ending the previous defrosting.
SiUS121827E
Part 4 Functions and Control