Units In The Heating Mode Do Not Operate At Expected Capacity - Mitsubishi Electric R410A Service Handbook

[8-3 Refrigerant Control Problems ]
8-3-2

Units in the Heating Mode Do Not Operate at Expected Capacity.

1. Phenomena
Although heating operation starts with the normal remote controller display, the capacity is not enough.
2. Cause, check method and remedy
1. Compressor frequency does not rise sufficiently.
Faulty detection of pressure sensor.
Protection works and compressor frequency does
not rise due to high discharge temperature
Protection works and compressor frequency does
not rise due to high pressure.
HWE14080
Cause
- 247 -
Check method and remedy
(1) Check pressure difference between the detected
pressure by the pressure sensor and the actual
pressure with self-diagnosis LED.
If the accurate pressure is not detected, check
the pressure sensor.
Refer to the following page(s). [8-5-1 Comparing
the High-Pressure Sensor Measurement and
Gauge Pressure](page 253)
Note: Higher inlet pressure by the high pressure sensor
than the actual pressure causes insufficient capac-
ity.
SW4 setting (SW6-10: OFF)
High pressure sensor
SW4
Low pressure sensor
SW4
For how to read the SW settings, refer to the fol-
lowing page(s). [9-1-1 How to Read the
LED](page 301)
(2) Check the difference between the condensing tem-
perature (Tc) and the target condensing tempera-
ture (Tcm) with self-diagnosis LED.
Note: Higher Tc than Tcm causes insufficient capacity.
SW4 setting (SW6-10: OFF)
Condensing temperature Tc
SW4
Target condensing temperature Tcm
SW4
For how to read the SW settings, refer to the fol-
lowing page(s). [9-1-1 How to Read the
LED](page 301)
Note: Protection works and compressor frequency does
not rise even at lower Tc than Tcm due to high dis-
charge temperature and high pressure.
At high discharge temperature:
Refer to the following page(s).[7-3-1 Error Code
[1102]](page 158)
At high pressure:
Refer to the following page(s).[7-3-3 Error Code
[1302] (during operation)](page 160)
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