Hitachi RAC-18SX8 Service Manual page 217

8.Timer lamp blinking: blinking once
[Situation] The timer lamp blinks once and the product will not run.
[Estimated failure locations]
[Diagnosis flow]
Description of the operation of the main circuit
See "latch-type reversing valve control circuit" (page 186).
[Caution] When conducting any of the following checks, be sure to turn off the power.
Is the reversing valve
connector (CN2) loose?
Detach the reversing valve
connector (CN2).
Measure the reversing valve
connector at both ends with a
tester. Does it indicate a
resistance of [400±100Ω]?
Is the 1 A fuse (F3) of the
board melted down?
Turn on the power supply,
perform "air purification" on
the indoor unit, press the "test
switch" of the indoor unit for at
least 1 second, perform
forcible cooling, and conduct a
voltage check while the
product is energized.
The problem may be a
defective reversing valve,
refrigerant leak, or
defective cycle.
・ Outdoor latch-type reversing valve control circuit out of order, reversing valve connector
loose, wire break
・ Latch-type reversing valve mechanically locked, coil wire break
・ Heat exchanger thermistor poorly installed (only during heating)
・ Cycle clogged (such as forgetting to open the service valve)
・ Refrigerant leakage
The product may enter this failure mode even when it is extremely hot (with a room
temperature of 40
less) and the refrigerant has almost run out. (The product cannot cool or heat at all.)
Yes
Connect the reversing
valve connector.
No
No
The problem should be
either a failure of the
reversing valve coil or a
wire break in the lead.
Yes
Yes
Replace the electrical
installation.
No
Abnormal
Replace the electrical
installation.
Normal
Check and correct the
failure location.
Double-check the operation and ensure that the product
works normally.
℃
or more) or extremely cold (with a room temperature of 5
– 250 –
Replace the reversing valve
coil.
℃
or