Mitsubishi PWFY-P36NMU-E-BU Service Handbook page 67

(2) Judgment methods and possible failure mode
Malfunction
mode
Microcomputer Disconnect the control board connector and connect
driver circuit fail- the check LED as shown in the figure below.
ure
resistance : 0.25W 1k
LED : DC15V 20mA or more
When the main power is turned on, the indoor unit cir-
cuit board outputs pulse signals to the indoor unit LEV
for 10 seconds, and the outdoor unit circuit board out-
puts pulse signals to the outdoor unit LEV for 17 sec-
onds.
If any of the LED remains lit or unlit, the drive circuit is
faulty.
LEV mechanism If the LEV is locked, the drive motor runs idle, and
is locked makes a small clicking sound.
When the valve makes a closing and opening sound,
the valve has a problem.
Disconnected or Measure resistance between the coils (red - white, red
short-circuited -orange, brown - yellow, brown - blue) using a tester.
LEV motor coil They are normal if resistance is 150ohm
Measure resistance between the coils (red - white, red
-orange, brown - yellow, brown - blue) using a tester.
They are normal if resistance is 46ohm
Incomple sealing To check the LEV for leakage, stop the unit in question,
(leak from the
and operate the other units in the cooling mode. Next,
valve)
check the temperature of the unit liquid pipe (TH22) on
the service LED. When the unit is stopped, the LEV is
fully closed, so unless there is a leak, the pipe temperature
will not go down. If the liquid pipe temperature is considerably
lower than the water temperature reading on the remote
controller, it indicates a valve closure failure. (The LEV
is not sealed properly.) If the amount of leakage is insignificant
and does not have negative effects, the valve does not
need to be replaced.
Faulty wire con- 1. Check for loose pins on the connector and check
nections in the the colors of the lead wires visually
connector or
2. Disconnect the control board's connector and
faulty contact
conduct a continuity check using a tester.
J u d g m e t n m e h t o d
6
5
4
3
2
1
1 k LED
3%.
Thermistor
(liquid piping
temperature detection)
Linear Expansion Valve
- 64 -
R e m
When the drive circuit has a
problem, replace the control
board.
Replace the LEV.
Replace the LEV coils.
10%.
Replace the LEV coils.
If there is a large amount of
leakage, replace the LEV.
Check the continuity at the
points where an error occurs.
e d y T a g r t e
LEV
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