Led Lighting Mode At The Thermistors Troubled - Hitachi RAM-55QH5 Service Manual

When the connectors of the thermistors are disconnected or the thermistors is open or short, LD301 (red) lights and
LD302 (red) blinks so that they indicate troubled parts. Combinations of LD301 and LD302 are set up for indicating troubled
thermistors. The correspondences between the number of blink time and troubled parts are shown as Table 10-3. Look in the
table (LD301 and LD302 blink) for troubled parts, and if the disconnections of them are checked out, they are replaced.
If you can see two or more troubled thermistors, a small number of blink takes precedence of others.
The electric expansions valve thermistor is put togrther with 3 pieces, when replacing the thermistor, replace one set of 3 pieces
as taking care of positioning. If you don't do so, the unit may not operate normally and its cooling and heating performance
may drop.
Be ware that only an open-circuit for OH thermistor has to be checked in 5 minutes after the compressor starts.
If the unit operates abnormally after replacing the thermistor, replace the control P.W.B. because it malfunctions.
LED lighting mode
LD301 LD302
Lights 1 blink
Lights 2 blinks
Lights 3 blinks
Lights 4 blinks
Lights 5 blinks
Lights 6 blinks
Lights 7 blinks
Lights 8 blinks
Lights 9 blinks
The OH thermistors are detecting the compressor head temperatures. If the temperature rises over 118˚C, the compressor
in the cycle will be stopped to protect itself and LD301 will blink 6 times (OH STOP). When the compressor temperature
fells under 105˚C, the compressor will restart. During OH STOP, the fan continues to spin. The other cycles without a
trouble operates normally.
If OH STOP often occurs, the refrigerant may be leaking.
Table 10-3 LED lighting mode at the thermistors troubled
Troubled thermistor
OH thermistor
DEF thermistor
Outdoor temperature thermistor
Electric expansion value thermistor (thin pipe 1)
Electric expansion value thermistor (thick pipe 1)
Electric expansion value thermistor (thin pipe 2)
Electric expansion value thermistor (thick pipe 2)
Electric expansion value thermistor (thin pipe 3)
Electric expansion value thermistor (thick pipe 3)
– 92 –
Judgement
Open Short
0.04V or less 4.96V or more
0.04V or less 4.94V or more
0.04V or less 4.94V or more