Liquid Compression Protection Function 2; Defrost Control - Daikin FT25CV1A Service Manual

Control for Heat Pump Models
3.9

Liquid Compression Protection Function 2

Outline In order to obtain the dependability of the compressor, the compressor must be stopped
according to the conditions of the temperature of the outdoor air and outdoor heat exchanger.
Detail
Compressor operation turns OFF under the conditions that the system is in cooling operation
and outdoor air temperature is below 0°C.
3.10

Defrost Control

Outline Heat Pump Only
Defrosting is carried out by the cooling cycle (reverse cycle). The defrosting time or outdoor
heat exchanger temperature must be more than its fixed value when finishing.
Detail Conditions for Starting Defrost
The starting conditions must be made with the outdoor air temperature and heat exchanger
temperature. Under the conditions that the system is in heating operation, 6 minutes after the
compressor is started and more than 32 minutes of accumulated time pass since the start of the
operation or ending the defrosting.
Conditions for Canceling Defrost
The judgment must be made with heat exchanger temperature. (4°C~24°C)
46
Operation stop depending on the outdoor air temperature
Frequency
ON
Compressor
OFF
ON
Four way valve
OFF
ON
Fan
OFF
Electronic expansion
valve opening
0Hz
180sec.
45sec. 450sec.
3sec.
55pps
30pps
75sec.
3sec.
40pps 55pps
Initial opening
Functions and Control
Si01-406
PI control
(R4121)