Check Of Outdoor Thermistor - Mitsubishi Electric MSH09TW Service Manual

When OPERATION INDICATOR lamp flashes 6-time.
Thermistors in the outdoor unit are abnormal.
G G Check of outdoor thermistor
W Disconnect the connector CN661 from the deicer P.C. board.
(Check the characteristics of thermistor.)
Defrost thermistor (RT61)
Turn OFF the
power supply.
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.
H H Check of R.V. coil
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)
Measure
Does the resistance
resistance
of thermistor have
between CN 661
the characteristics
1 and 2.
on page 96?
Replace the
thermistor.
(MUH09/12/15/17)
Turn ON the power supply and operate
the indoor unit in HEAT mode by pressing
the EMERGENCY OPERATION switch.
After 3 minutes, does the unit
operate in COOL mode?
Yes
Is there 115V AC (MUH09), 208/230V AC
(MUH12/15/17) between CN7211 – 2 on
the deicer P.C. board?
Refer to page 96.
Yes
Replace the R.V. coil.
(MUH09/12/15/17)
Turn ON the power supply and operate
the indoor unit in COOL mode by pressing
the EMERGENCY OPERATION switch.
After 3 minutes, does the unit
operate in HEAT mode?
Yes
Is there 115V AC (MUH09), 208/230V AC
(MUH12/15/17) between CN7211 – 2 on
the deicer P.C. board?
Refer to page 96.
Yes
Replace the
deicer P.C. board.
Re-connect CN661.
Turn ON the power
Yes
supply and press
the EMERGENCY
OPERATION
switch.
No
3 Defective contact of the connector is considered.
No
OK
No
Replace the
deicer P.C. board
No
OK
No
Replace the R.V. coil.
88
Replace the deicer P.C.
board.
No
Does the unit operate
10 minutes or more?
Yes
Ok 3