Mitsubishi Electric MUZ-FA25VA-E1 Service Manual page 37

Outdoor unit does not operate at all, or stops immediately due to overcurrent.
Check of current-limiting resistor
K
When the current-limiting resistor is open, the rush current limiting relay (X64) may not work properly.
Is the resistance of current-limiting
resistor (R64A or R64B) on the
power P.C. board normal?
(Normal resistance : 5' i5%)
No
Replace the power P.C. board.
Check other electric parts in the main circuit together in the case that the current-limiting resistor is defective.
Heating/Cooling does not work sufficiently.
Check of LEV (Expansion valve)
L
Turn ON the power supply.
< Preparation of the remote controller >
1 While pressing both OPERATION SELECT
button and TOO COOL button on the remote
controller at the same time, press RESET button.
2 First, release RESET button.
And release the other two buttons after all LCD
except the set temperature in operation display
section of the remote controller is displayed after
3 seconds.
Press OPERATE/STOP(ON/OFF) button of the remote
controller (the set temperature is displayed) with the
remote controller headed towards the indoor unit. W1
Expansion valve operates in
full-opening direction.
Do you hear the expansion
valve "click, click·······"?
Do you feel the expansion
valve vibrate on touching it ?
No
Is LEV properly fixed to the
expansion valve?
Yes
Does the resistance of LEV
have the characteristics?
Refer to 11-5.
No
Replace the LEV.
NOTE : After check of LEV, do the undermentioned operations.
1. Turn OFF the power supply and turn ON it again.
2. Press RESET button on the remote controller.
Turn ON the power
Yes
supply and press
EMERGENCY
OPERATION switch.
Yes
Ok
No
Properly fix the LEV to the
expansion valve.
Measure each voltage between connector pins
of CN724 on the inverter P.C. board.
1.Pin3(-) Pin1(+)
Yes
2.Pin4(-) Pin1(+)
3.Pin5(-) Pin1(+)
4.Pin6(-) Pin1(+)
Is there about 3~5V AC between each?
NOTE: Measure the voltage by an analog tester.
Replace the
expansion valve.
Does LED on the inverter
P.C. board light up?
Yes
Does the rush current
limiting relay(X64) work
properly? (Normally it
closes 1 second after
outdoor unit power ON.)
No
Replace the power P.C.board.
No
Replace the
inverter P.C. board.
Yes
37
No Replace the power P.C.
board or the inverter P.C.
board.
Yes
Replace the inverter P.C.
board or the compressor.
W1. Regardless of normal or abnormal condition,
a short beep is emitted once the signal
is received.