Mitsubishi Electric City Multi PQHY-P72 Service Handbook page 231

[ IX Troubleshooting ]
Error Code
2135 Water heat ex-
changer freez-
ing
Error definition and error
detection method
1. If the following condi- (1) Heat source water pump
tions are met during
(1st time) the opera- (2) Problems with the heating
tion, the heat source
unit comes to a stop, (3) Dirty or clogged water heat
goes into 3-min. re-
start prevention mode, (4) Broken lead wire for water
and restarts after
three minutes.
[Conditions] (5) Disconnected connector
Detection of the tem-
perature of 3°C[37°F]
or below by the water (6) Failure of the water heat
heat exchanger outlet
pipe sensor (TH9), or
the detection of the
compressor frequency (7) Failure of the water heat
of lower than the mini-
mum frequency 20Hz
+10 and the fifteen
continuous minutes of
evaporating tempera-
ture Te detection of
higher than -10°C [14
°F] .
2. If the above conditions
are met (2nd time)
within sixty minutes of
the stoppage of heat
source unit, the unit
comes to an abnormal
stop and displays the
code "2135."
3. If the above conditions
are met (2nd time) af-
ter sixty minutes have
passed since the stop-
page of heat source
unit, it is considered
as the first detection,
and the same se-
quence of operation
as the one in item 1
above is followed.
- 222 -
Cause
failure
device
exchanger
heat exchanger freeze
prevention Thermo
for water heat exchanger
freeze prevention Thermo
exchanger freeze preven-
tion Thermo input circuit
on the relay board
exchanger freeze preven-
tion Thermo input circuit
on the control board
Check method and remedy