88
G
G
Check of outdoor thermistor
H
H
Check of R.V. coil
Unit operates COOL mode even if it is set to HEAT mode.
w
First, measure the resistance of R.V. coil to confirm it is disconnected or is not short-circuit.
W
Disconnect the connector CN661 from the deicer P.C. board.
(Check the characteristics of thermistor.)
When OPERATION INDICATOR lamp flashes 6-time.
Thermistors in the outdoor unit are abnormal.
Measure
resistance
between CN 661
1
and
2
.
No
Yes
Replace the
thermistor.
Defrost thermistor (RT61)
Re-connect CN661.
Turn ON the power
supply and press
the EMERGENCY
OPERATION
switch.
Does the resistance
of thermistor have
the characteristics
on page 96?
No
Yes
Does the unit operate
10 minutes or more?
Replace the deicer P.C.
board.
Ok
❈
3
❈
3 Defective contact of the connector is considered.
Turn OFF the
power supply.
After 3 minutes, does the unit
operate in COOL mode?
OK
Yes
Yes
No
After 3 minutes, does the unit
operate in HEAT mode?
OK
No
Replace the
deicer P.C. board
No
Replace the R.V. coil.
Turn ON the power supply and operate
the indoor unit in HEAT mode by pressing
the EMERGENCY OPERATION switch.
Is there 115V AC (MUH09), 208/230V AC
(MUH12/15/17) between CN721
1
–
2
on
the deicer P.C. board?
Refer to page 96.
Replace the
deicer P.C. board.
Yes
Yes
No
Replace the R.V. coil.
Turn ON the power supply and operate
the indoor unit in COOL mode by pressing
the EMERGENCY OPERATION switch.
Is there 115V AC (MUH09), 208/230V AC
(MUH12/15/17) between CN721
1
–
2
on
the deicer P.C. board?
Refer to page 96.
Unit operates HEAT mode even if it is set to COOL mode.
w
First, measure the resistance of R.V. coil to confirm it is disconnected or is not short-circuit.
H
H
Check of R.V. coil
(MUH09/12/15/17)
(MUH09/12/15/17)
(MUH09/12/15/17)
OB275--3.qxp 03.12.2 5:19 PM Page 88
Summary of Contents for MSH09TW
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