Mitsubishi Heavy Industries FDT28KXE6A User manual

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Manual No. '09·KX-SM -128
INVERTER DRIVEN MULTI-INDOOR UNIT
CLIMATE CONTROL SYSTEM
SERVICE MANUAL
Alternative refrigerant R410A use models
(OUTDOOR UNIT)
• Single use (Used also for combination)
FDC335KXE6-K, 400KXE6, 450KXE6, 504KXE6, 560KXE6, 560KXE6-K, 615KXE6, 680KXE6
• Combination use
FDC753KXE6, 800KXE6, 850KXE6, 900KXE6, 960KXE6, 1010KXE6, 1065KXE6, 1130KXE6,
1180KXE6, 1235KXE6, 1300KXE6, 1360KXE6
(Heat pump type)
KX6 series
FDT28KXE6A
36KXE6A
45KXE6A
56KXE6A
71KXE6A
90KXE6A
112KXE6A
140KXE6A
160KXE6A
FDUM22KXE6
28KXE6
36KXE6
45KXE6
56KXE6
71KXE6
90KXE6
112KXE6
140KXE6
FDUH22KXE6
28KXE6
36KXE6
FDTC22KXE6A
28KXE6A
36KXE6A
45KXE6A
56KXE6A
FDQS22KXE6
28KXE6
36KXE6
45KXE6
56KXE6
FDU71KXE6
90KXE6
112KXE6
140KXE6
224KXE6
280KXE6
FDFU28KXE6
45KXE6
56KXE6
71KXE6
FDTW28KXE6
45KXE6
56KXE6
71KXE6
90KXE6
112KXE6
140KXE6
FDK22KXE6
28KXE6
36KXE6
45KXE6
56KXE6
71KXE6
FDTQ22KXE6
28KXE6
36KXE6
FDFL28KXE6
45KXE6
71KXE6
FDTS45KXE6
71KXE6
FDE36KXE6A
45KXE6A
56KXE6A
71KXE6A
112KXE6A
140KXE6A
(INDOOR UNIT) - KX6 series -
Regarding the Duct Connected-High static Pressure-type Outdoor Air Processing
Unit Series (FDU500〜1800FKXE6), refer to the DATA BOOK No.'08
• KX-DB-122
• Note
updated November 19, 2009

CONTENTS
1 OUTLINE OF OPERATION CONTROL BY MICROCOMPUTER..................... 1
1.1 Wired remote controller (Option parts)...................................................... 1
1.2 Operation control function by the indoor controller ...................................2
1.3 Operation control function by the remote controller ..................................8
1.4 Operation control function by the outdoor controller.................................9
2 SYSTEM TROUBLESHOOTING PROCEDURE............................................. 45
2.1 Basics of troubleshooting........................................................................ 45
2.2 Explanation of troubleshooting................................................................46
2.3 Contents of troubleshooting....................................................................47
2.4 Outdoor unit control PCB replacement procedure ................................101
2.5 Inverter PCB replacement procedure.................................................... 103
3 ELECTRICAL WIRING .................................................................................. 107
3.1 Indoor unit ............................................................................................. 107
3.2 Outdoor unit .......................................................................................... 129
4 PIPING SYSTEM............................................................................................ 130
5 APPLICATION DATA.................................................................................... 131
5.1 Installation of indoor unit........................................................................... 131
(a) Ceiling cassette-4 way type (FDT)..................................................... 132
(b) Ceiling cassette-4 way compact type (FDTC)....................................137
(c) Ceiling cassette-2 way type (FDTW) ................................................. 142
(d) Ceiling cassette-1 way type (FDTS) .................................................. 145
(e) Ceiling cassette-1 way compact type (FDTQ) ................................... 148
(f) Duct connected-High static pressure type (FDU) .............................. 151
(g) Duct connected-Middle static pressure type (FDUM)........................157
(h) Duct connected (Ultra thin)-Low static pressure type (FDQS)........... 160
(i) Wall mounted type (FDK) ..................................................................163
(j) Ceiling suspended type (FDE)........................................................... 166
(k) Floor standing (with casing) type (FDFL)........................................... 169
(l) Floor standing (without casing) type (FDFU).....................................172
(m) Duct Connected-Compact and Flexible type (FDUH)........................ 175
5.2 Electric wiring work instruction.................................................................. 178
5.3 Installation manual of wired remote controller (Option parts)...................184
5.4 Installation of outdoor unit.........................................................................188
5.5 Instructions for installing the branch pipe set............................................211

– 1–
1. OUTLINE OF OPERATION CONTROL BY MICROCOMPUTER
1.1 Wired remote controller (Option parts)
The gure below shows the remote controller with the cover opened. Note that all the items that may be displayed in the liquid crystal
display area are shown in the gure for the sake of explanation.
Characters displayed with dots in the liquid crystal display area are abbreviated.
Pull the cover downward to open it.
＊ All displays are described in the liguid crystal display for explanation.
The figure below shows the remote control with the cover opened.
Installation of remote control
DO NOT install it on the following places in order to avoid malfunction.
(1) Places exposed to direct sunlight
(2) Places near heat devices
(3) High humidity places
(4) Hot surface or cold surface enough to generate condensation
(5) Places exposed to oil mist or steam directly
(6) Uneven surface
Cover
This button is used to fix the setting.
This button is used to set the silent mode.

– 2–
1.2 Operation control function by the indoor controller
(1) Operations of functional items during cooling/heating
Cooling Heating
Dehumidify
Fan
Operation
Functional item
Thermostat
ON Thermostat ON
Thermostat
OFF Thermostat OFF Hot start (Defrost)
Compressor
4-way valve
Outdoor fan
Indoor fan
Louver motor
Drain pump (4)











/
(2)




(2)




/ 
/




/ 
/
/(2)

()
()

/ 
/
/

/
/
/
Thermostat ON: 
Thermostat OFF: (2)
Note (1) : Operation : Stop /: Turned ON/OFF by the control other than the room temperature control.
(2) ON during the drain motor delay control
(3) Drain pump ON setting may be selected by the indoor unit function setting of the wired remote controller.
(2) Dehumidifying operation
(a) When the humidity sensor is not provided (Models other than FDT Series)
return air thermistor [ThI-A (by the remote controller when the remote control sensor is enabled)] controls the indoor
temperature environment simultaneously.
1) Operation is started in the cooling mode. When the difference between the return air thermistor and the setting
temperature is 2°C or less, the indoor unit fan tap is brought down by one tap. That tap is retained for 3 minutes
after changing the indoor fan tap.
2) If the suction air temperature exceeds the setting temperature 3°C or more during defrosting operation, the indoor
fan tap is raised by one tap. That tap is retained for 3 minutes after changing the indoor fan tap.
3) If the thermostat OFF is established during the above control, the indoor fan tap at the thermostat ON is retained so
far as the thermostat is turned OFF.
4) After stopping the cooling operation, the indoor unit continues to run at Lo for 15 seconds.
(b) When the humidity sensor is provided (FDT Series only) [Optional]
1) Operation starts in the cooling mode, and the target relative humidity is determined based on the setting temperature.
If the humidity detected by the humidity sensor becomes lower than the target relative humidity, the indoor unit fan
tap is retained.
2) Anything other than 1) above is same as the item (a) above.
(3) Timer operation
(a) Timer
Set the duration of time from the present to the time to turn off the air-conditioner.
It can be selected from 10 steps in the range from “OFF 1 hour later” to “OFF 10 hours later”. After the clock timer
setting, the remaining time is displayed with progress of time in the unit of hour.
(b) OFF timer
Time to turn OFF the air-conditioner can be set in the unit of 10 minutes.
(c) ON timer
Time to turn ON the air-conditioner can be set. Indoor temperature can be set simultaneously.
(d) Weekly timer
Timer operation (ON timer, OFF timer) can be set up to 4 times a day for each weekday.
(e) Timer operations which can be set in combination
Timer
OFF timer
ON timer
Weekly timer
Timer



OFF timer



ON timer



Weekly timer



Note (1) : Allowed : Not

– 3–
(4) Remote controller display during the operation stop
(a) “Centralized control ON” is displayed always on the LCD under the “Center/Remote” and “Center” modes during the
operation stop (Power ON). This is not displayed under the “Remote” mode.
(b) If this display is not shown under the “Center/Remote” mode, check if the indoor unit power switch is turned on or not.
(5) Hot start (Prevention of cold draft during heating)
At the startup of heating operation, at resetting the thermostat, during defrosting operation and at returning to heating, the
indoor fan is controlled by the indoor heat exchanger temperature (detected with ThI-R) to prevent the cold draft.
Judgment by heating start thermostat
Normal condition/Set airflow volume
Thermostat OFF Thermostat ON
Compressor OFFCompressor ON End of defrosting
Heat exchanger temp. 35˚C or higher, or after 7 minutes Heat exchanger temp. 35˚C or higher, or after 7 minutes
Defrosting start
Fan
Lo
Lo
Set airflow volume
Set airflow volume
Indoor heat exchanger temp. (˚C)
Indoor heat exchanger temp. (˚C)
35
35 45
25 35
Indoor heat exchanger temp. (˚C)
Set airflow volume
Fan
OFF
Lo
25 35 45
Set airflow volume
Fan
OFF
Indoor heat exchanger temp. (˚C)
Fan
Lo
（1）
Note (1) Heating preparation is displayed during the hot start (when the compressor is operating and the indoor fan does not provide the set airow volume).
(6) Hot keep
Hot keep control is performed at the start of the defrost control.
(a) Control
1) When the indoor heat exchanger temperature (detected with ThI-R1 or R2) drops to 35°C or lower, indoor fan is
changed to the lower tap at each setting.
2) During the hot keep operation, the louver horizontal control signal is transmitted.
(b) Ending condition
When the indoor fan is at the lower tap at each setting, it returns to the set airow volume as the indoor heat exchanger
temperature rises to 45°C or higher.
(7) Fan control during the heating thermostat OFF
When the heating thermostat is turned OFF, the setting of the fan control is selectable with using the indoor function of wired
remote controller [Heating fan control].
(a) Low speed (Factory default)
If the indoor heat exchanger temperature drops 35°C or lower with the heating thermostat OFF, the indoor fan operate at
the lower speed tap at each setting.
(b) Set airow volume
Even if the indoor heat exchanger temperature drops 35°C or lower with the heating thermostat OFF, the indoor fan
continues to run at the set airow volume.
(c) Intermittent operation
If the indoor heat exchanger temperature drops 35°C or lower with the heating thermostat OFF, the indoor fan operates at
the lower speed tap at each setting and, when the indoor heater exchanger temperature drops 25°C or lower, the indoor fan
stops for 5 minutes. Then the fan runs at the slow speed tap for 2 minutes, and the judgment is made by the thermostat.
(d) Stop
If the indoor heat exchanger temperature drops 35°C or lower with the heating thermostat OFF, the indoor fan is turned
OFF. The same applies also when the remote controller sensor is effective.