Friedrich MW09C1H Service Manual page 54

Troubleshooting
Fault diagnosis process:
Energize and
switch on
IPM protection
occurs after the
machine has run for
a period of time?
Please confirm:
1. If the indoor and
outdoor heat
exchangers are
dirty? If they are
obstructed by other
objects which affect
the heat exchange
of indoor and
outdoor unit.
2. If the indoor and
outdoor fans are
working normally?
3. If the environment
temperature is too
high, resulting in
that the system
pressure is too high
and exceeds the
permissible range?
4. If the charge
volume of
refrigerant is too
much, resulting in
that the system
pressure is too
high?
5. Other conditions
resulting in that the
system pressure
becomes too high.
Refer to the
Electrical Wiring
Diagram and check
if the connection
between AP1 and
COMP is loose and if
the connection order
is correct.
If the connection
between AP1 and
COMP is unsecure
or the connection
order is wrong?
Use ohmmeter to
measure the resistance
between the three
terminals on compressor
COMP, and compare the
measurements with the
compressor resistance on
Service Manual.
Use ohmmeter to
measure the resistance
between the two
terminals of compressor
COMP and copper tube.
54
Use AC voltmeter
to measure the
voltage between
Y
terminal L and N
on the wiring
board XT)
Voltage between
the two ends of
electrolytic
Y
capacitor (test3) is
higher than 250V
N
Stop the unit
disconnect the power
supply. Then, check
the connection
capacitor C2
according to Electrical
Wiring Diagram.
Remove the wires
on the two ends of
capacitor C2. Then,
use capacitance
meter to measure
the capacitor C2.
Verify as per the
Parameters Sheet.
If capacitor
C2 is failed?
N
If there is any
abnormality
described above?
Connect the control panel
AP1 and compressor
COMP correctly according
Y
to the Electrical Wiring
Diagram. Then, energize
and start the unit.
If the
resistance is
normal?
Resistance higher
than 500M ?
control panel
If the voltage
between terminal L
and N on wiring
board XT is within
210VAC~250VAC?
Y
Start and run the
unit. Before
protection occurs,
use DC voltmeter to
measure the voltage
between the two
ends of electrolytic
capacitor on control
panel AP1 (test3)
and
The connection
of of capacitor C2
is loose.
N
Stop the unit and
disconnect the power
supply. Wait 20 minutes,
or use DC voltmeter to
measure the voltage
between the two ends of
capacitor C2, until the
voltage is lower than 20V
Replace the capacitor
C2. Then, energize
Y
and start the unit.
Replace the
control panel AP1
Take corrective actions
according to Technical
Y
Service Manual, and
then energize and start
the unit.
Replace the
N
control panel AP1
If the unit can
Replace the
compressor
N
COMP
N
N
Replace the
AP1
END
Check the supply
voltage and
N
restore it to
210VAC~250VAC
If the unit can
work
N
normally?
Reconnect the
capacitor C2 according
to Electrical Wiring
Y
Diagram. Then,
energize and start the
unit.
If the unit can
N
work
normally?
If the unit can
work
normally?
N
If the unit can
work
normally?
N
work
normally?
Y
Y
Y
Y
Y