Panasonic NR-B420M Service Manual page 5

Continuity
Continuity
VIEW WINDOW
(to check gear moving)
Check if the timer motor is
properly running through the
"VIEW WINDOW" located at
the side of timer body. You can
see the gear moving.
Moving.
Short circuit orange (2) and brown (1)
terminals of timer (both ends of
bimetal will be short circuited), and
confirm that defrosting heater heats up.
Check fan motor
continuity.
Rotating
direction
Cam shaft
Not movimg.
Manually set timer to
condition A. and confirm
that defrost heater heats up.
Does not heat up.
---- 5 ----
Turn the COLD AIR CONTROL
to D or E.
Turn the COLD AIR CONTROL
to A or B.
Replace door switch
No contiunity
Replace fan motor
(broken coil).
Repair cooling unit
(initial gas leakage).
Replace bimetal
thermostat (broken).
Excessive door gap.
Door open for long
period.
Replace timer
(broken coil).
Heats up.
Replace timer
(faulty operationl).
Heats up. Replace bimetal thermostat
(does not switch ON).
Does not
heats up.
Replace timer (no continuity
between defrosting contacts).
B420M/MS/MW, B480M/MS/MW,
B570M/MS/MW/D/D-*9, B53D2,
B643M/MS/MW/D/D-*9, B703M/MS/MW,
C603D, C703M/MS/MW/D