Mitsubishi Electric PURY-HP144, Service Handbook

Page: 141 / 398

[5-2 Outdoor Unit Control ]
16
- chapter 5 HWE18220_GB
5 Control
(3) Stopping the defrost operation
Œ
The defrost cycle ends when 12 minutes have passed
*1
since the beginning of the cycle, or when the pipe temperatures (TH3)
have been continuously detected for 4 minutes (when SW4 (916) is set to OFF) or 2 minutes (when SW4 (916) is set to ON)
that exceeds the values in the table below.
Œ
The defrost cycle will not end for two minutes once started unless one of the following conditions is met: Pipe temperature
reaches 25°C [77°F] and SW4 (916) is set to OFF OR
Į
*2
=25°C+TH7°C [77°F+TH7°F] and SW4 (916) is set to ON.
Œ
In the multiple-outdoor-unit system, defrosting is stopped on all units at the same time.
*1 The compressor frequency is fixed at 60Hz when the compressor bottom SH (TH15 - Te)
”
10ºC [18ºF]. And the defrost
mode may continue even after 12 minutes.
*2 (5°C [41°F]
” Į ”
25°C [77°F]).
(4) Problems during defrost operation
Œ
If a problem is detected during defrost operation, the operation will be stopped, and the defrost prohibition time based on the
integrated compressor operation time will be set to 20 minutes.
Œ
The unit will stop after the defrost operation when the total time of “compressor bottom SH (TH15 – Te)
”
10ºC [18ºF]” reaches
3 minutes.
(5) Change in the number of operating indoor units during defrost operation
Œ
Even when there is a change in the number of operating indoor units during defrost operation, the operation will continue, and
an adjustment will be made after the completion of the defrost operation.
Œ
Defrost operation will be continued, even if the indoor units stop or under the Thermo-OFF conditions until it has run its course.
Model
TH3
SW4 (916) OFF SW4 (916) ON
HP72 - HP120 models 7°C [45°F] 12°C [54°F]