Toshiba RAS-18UAX - 8-4-4 Under Ceiling Installation

FILE NO. SVM-02008
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9-5. How to Diagnose Faulty Parts
[04 Serial signal error]
[08 Four-way valve error]
Does outdoor
unit operate?
Are 1, 2 and 3 crossover
wires connected properly?
Is connector
connected properly?
Does LED (Orange) on
outdoor P.C. board blink?
Does LED (Green) on
outdoor P.C. board blink?
Connect crossover
wires properly.
Outdoor P.C. board
is defective.
Replace
P.C. board.
YES
NO
YES
NO
YES
NO
YES
NO
YES
NO
Does four-way valve
operate properly?
Is TC sensor resistance
value (10kΩ at 25°C)
normal?
Does coil terminal
have 220 – 240 V
in heating operation?
Are circuit
wires normal?
Is outdoor P.C. board
normal?
Four-way valve
is defective.
Outdoor P.C. board
is defective.
(CN11 220 – 240V)
Replace
Four-way valve
Circuit check/modification
Replace TC sensor.
YES
NO
YES
NO
YES
YES
NO
NO
YES
NO
Operation
Measure
Item by symptoms
Check item
Conceivable principle
cause
Indoor P.C. board
is defective.
Replace
P.C. board.
Indoor P.C. board
is defective.
Replace
P.C. board.
Replace
P.C. board.
Connect crossover
properly.