Mitsubishi MUX-2A28VB Service Manual page 61

Cool air does not blow out although indoor unit is operating.
D D Check of indoor/outdoor units' connection and outdoor unit
w In case of troubleshooting, be sure to operate indoor unit by emergency operation switch.
Start
Turn ON the power supply, and operate all the indoor
units at a time.
Do they perform the cooling operation?
Yes
Operate the indoor unit one by one, and measure
the voltage between 1 and 2 of outdoor
terminal block for each indoor unit.
Match the signs of terminal block whose voltage is
12V DC and pipe of indoor/ outdoor units' connection.
w1.
w1. MUX-2A28/3A60/3A63/4A73VB
If the pipe of indoor unit that does not operate is cooled
though the combination of pipe and connecting wire is correct,
check the solenoid coil. Refer to 7.WIRING DIAGRAM.
Indoor
Model
unit
A
MUX-2A28VB
B
B
MUX-3A60VB
MUX-3A63VB C
A
B
MUX-4A73VB
C
D
Turn OFF the power supply.
No
Remove solenoid coil's connector that corresponds
to the indoor unit, which does not blow out cool air.
Then, measure the resistance of solenoid coil.
Do the resistance value normal?
(Refer to 11-3.)
Reconnect solenoid coil's connector.
Then turn the main power on and operate the
indoor unit that does not blow out cool air.
Measure the voltage of solenoid coil's connector that
corresponds to the indoor unit, which is operated.
Terminal Connector for
block solenoid coil control
TB2
21R1
21R
TB2
21R2
TB3
21R3-CN85
21RB-CN81
TB4
21R4-CN86
TB2
21R1-CN83
21RA-CN82
TB3
21R2-CN84
TB4
21R3-CN85
21RB-CN81
TB5
21R4-CN86
No
Yes
No
MUX-2A28VB
Is voltage 230V?
Yes
OK
MUX-2A59/3A60/3A63/
2A70/4A73VB
61
Replace the solenoid coil.
Check wiring of outdoor
unit and relay. (Refer to page 16.)
Replace the outdoor
control P.C. board.