Mitsubishi Electric PUHY-P120YHMU-A, Service Manual

Page: 237 / 326

[
IX
Troubleshooting ]
- 228 - HWE0804A GB
2. Phenomena
Although heating operation starts with the normal remote controller display, the capacity is not enough.
(1) Cause, check method and remedy
Cause Check method and remedy
1. Compressor frequency does not rise sufficiently.
ΠFaulty detection of pressure sensor.
ΠProtection works and compressor frequency does
not rise due to high discharge temperature
ΠProtection works and compressor frequency does
not rise due to high pressure.
(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 page on Trouble-
shooting of Pressure Sensor)
Note: Higher inlet pressure by the high pressure sensor
than the actual pressure causes insufficient capac-
ity.
SW1 setting
(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.
SW1 setting
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 1102.(page 154)
At high pressure:
Refer to 1302.(page 156)
High pressure sensor
Low pressure sensor
ON
1 2 3 4 5 6 7 8 9 10
ON
1 2 3 4 5 6 7 8 9 10
SW1
SW1
Condensing temperature Tc
Target condensing temperature Tcm
ON
ON
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
SW1
SW1