Mitsubishi Electric PUHY-HP72 Service Handbook page 101

[5-2 Outdoor Unit Control ]
(2) Defrost operation
Compressor frequency
Outdoor unit fan
SV1a
21S4a
21S4b
SV2
SV9
SV10
LEV1
LEV2a, b
LEV4
*1. This value may be greater than 0 pulse depending on the 63LS and TH4 status.
(3) Stopping the defrost operation
The defrost cycle ends when 12 minutes have passed since the beginning of the cycle, or when the pipe temperature (TH3)
has 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.
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
*1 (5°C [41°F] 25°C [77°F]).
In the multiple-outdoor-unit system, defrosting is stopped on all units at the same time.
Model
HP72 - HP120 models
(4) Problems during defrost operation
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.
(5) Change in the number of operating indoor units during defrost operation
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.
Defrost operation will be continued, even if the indoor units stop or under the Thermo-OFF conditions until it has run its course.
14
- chapter 5
Model
Standard HP72 model
HP96 model
HP120 model
*1
=25+TH7°C [77°F+TH7] and SW4 (916) is set to ON.
TH3
SW4 (916) OFF
7°C [45°F]
Compressor frequency
103 Hz
113 Hz
113 Hz
Stopped
ON
OFF
OFF
ON
ON
OFF (Closed)
*1
0 pulses
3000 pulses
0 pulses
SW4 (916) ON
5°C [41°F]
HWE18240_GB