How To Check Mis-Wiring And Serial Signal Error; Check Of Outdoor Thermistor - Mitsubishi Electric MSH-C18TV Service Manual

How to check mis-wiring and serial signal error

G
Outdoor unit doesn't operate.
Repair wiring.
Is there 20V DC between both ends of R132 when
52C contactor turns ON?
( By tester, the stylus is between 0 ~ 20V. )
Yes
1. Turn OFF the power supply.
2. Re-connect in-out connecting wire.
3. Turn ON the power supply.
3 minutes later, when the EMERGENCY OPERATION switch is
pressed and 52C contactor turns ON, is there 230V AC between the
outdoor terminal block -
N
2
Yes
Is there 5V DC between J8
+
J401 - J101 (MSH-C24TV) on the deicer P.C.
–
board?(Refer to page 45 or 46.)
Yes
Is there 10V DC between both ends of
R601?(Refer to page 45 or 46.)
(By tester, the stylus is between 5 ~10V)
Yes
Replace the deicer P.C. board.

Check of outdoor thermistor

H
Thermistors in the outdoor unit are abnormal.
W Disconnect the connector CN661 and CN662 from the deicer P.C. board.
(Check the characteristics of each thermistor.)
Turn OFF the
power supply.
1. Turn OFF the power supply.
2. Turn ON the power supply.
3. Press the EMERGENCY OPERATION switch.
3 min. later, when 52C contactor turns ON, what self-check result is
displayed on OPERATION INDICATOR lamp on the indoor unit?
Yes
Is there mis-wiring, poor contact, or wire disconnection?
1. Turn OFF the power supply and disconnect in-out connecting wire on the indoor side.
2. Short-circuit between indoor terminal block
3. Turn ON the power supply and press the EMERGENCY OPERATION switch.
No
? 2
+
– -J9 (MSH-C18TV) / No
2
No
2
Defrost thermistor (RT61)
Measure
resistance
between CN 661
1 and 2.
<MSH-C24TV only>
Ambient
temperature
thermistor (RT63)
Measure
resistance
between CN 662
3 and 4.
Start
Mis-wiring is indicated.(0.5-sec.ON, 0.5-sec.OFF)
No
and .
3
N
No
Re-connect CN661
and CN662.
Turn ON the power
Does the resistance
Yes
supply and press
of thermistor have
the characteristics
the EMERGENCY
on page 45 or 46?
OPERATION
switch.
No
Replace the
thermistor.
43
1 Short circuit of JPG and JPS on the
indoor electronic control P.C. board
enables self-check to be displayed in 3
seconds.
Serial signal error is indicated.
(0.5-sec.ON, 2.5-sec.OFF)
1
Replace the indoor electronic control
P.C. board.
Rectify in-out connecting wire.
Check and rectify the fuse and the varistor
on the deicer P.C. board.
Rectify in-out connecting wire.
2 While the serial signal error is indicated,
52C contactor alternates ON for about 10
seconds and OFF for 3 minutes.
Measure the voltage when 52C contactor
is ON.
Replace the deicer P.C.
board.
Does the unit operate
10 minutes or more?
Ok
3 It is thought defective contact of the connector.
No
Yes
3