Mitsubishi Heavy Industries FDT28KXE6A Service Manual page 33

(C) Data output
(1) 7-segment display and operation data retention
(a) 7-segment display
Operation information is displayed for checking various operation data during test run and for helping malfunction diag-
nosis at servicing. Input data to microcomputer, contents of outdoor unit control, registration information of indoor units
and etc. are mainly displayed on the 7-segment LED.
(i) Operation information display
1) Each item is displayed at the 7-segment LED with 6-digit on outdoor contol PCB
2) Left 3 digits are for code display and right 3 digits are for data display
3) The code No. of each item is selected by pressing SW9 for the order of 10 and SW8 for the order of 1.
4) If the code No. is set at "C99", the data of the code No. from "C00" to "C29" is displayed cyclically.
Code No. at factory setting is "C99"
5) If the code No. is set at other than "C99", the data of selected code No. is kept on displaying.
6) The code No. "C77" is for resetting
The contents of retained operation data (the data for a period of 30 minutes prior to error stop) can be erased by
setting the code No. at "C77".
The resetting method is to select the code "C77" first. (If any error data is retained, "dEL" is displayed on the
data display area.)
And then when press SW7 for 3 seconds, the retained error data can be erased. However the data of the code No.
"C54" and "C55" (compressor cumulative operation time) are not erased.
When the data is erased, "---" is displayed on the data display area of 7-segment LED. And this is displayed as
well when no error data is retained.
7) If SW8 (order of 1) is pressed, it displays in the order of 0 ⇒ 1 ⇒ 2 ...... 9 ⇒ 0.
8) If SW9 (order of 10) is pressed, it jumps to the leading code of each order of 10
(Example) If SW9 is pressed at the code No. "C07" displayed, it jumps to the code No. "C10".
9) The data of code No. "C54" and "C55" can be erased independently
The compressor cumulative operation time corresponding to the code No. selected can be erased (reset). (For
resetting of the compressor cumulative operation time after replacement of compressor)
The resetting method is to select the code "C54" or "C55" first. (the compressor cumulative operation time
corresponding to the code No. is displayed on the data display area of 7-segment LED.)
And then when press SW7 for 3 seconds, the retained data can be erased. However the data of the retained operation
data (the data for 30 minutes before error stop) are not erased.
(ii) Individual definition of display contents
1) Code No. "C17": Subcooling degree at cooling mode
[Subcooling degree at cooling mode] =
[High pressure saturated temperature detected with high pressure sensor (PHS)]
-[ Subcooling coil temperature detected with subcooling temperature thermistor (Tho-SC)]
The calculated result is displayed after rounding to one decimal place. Or if the calculated result is a negative
value, "0.0" is displayed.
During heating mode this data might be unreliable as subcooling degree, but the result is displayed as it is.
2) Code No. "C18": Suction superheat degree
[Suction superheat degree] =
[Suction pipe temperature detected with suction pipe temperature thermisot (Tho-S)]
-[Low pressure saturated temperature detected with low pressure sensor (PLS)]
The calculated result is displayed after rounding to one decimal place. Or if the calculated result is a negative
value, "0.0" is displayed.
3) Code No. "C19": Superheat degree of subcooling coil
[Superheat degree of subcooling coil] =
[Subcooling coil temperature detected with subcooling coil temperature thermistor (Tho-H)]
-[Low pressure saturated temperature detected with low pressure sensor (PLS)]
The calculated result is displayed after rounding to one decimal place. Or if the calculated result is a negative
value, "0.0" is displayed.
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