Hitachi RAS-(4-12)HNP(1)(E) - Heating Overload (High Pressure Switch will be Activated) for RAS-(2-2.5)HVNP1 and RAS-3 HVNC1

8 Troubleshooting
256
SMGB0087 rev.0 - 12/2013
Alarm code
42
Heating Overload (High pressure switch will be activated) for RAS-(2-2.5)HVNP1 and RAS-3HVNC1
- Abnormality indication will appear when the protection device is activated during compressor operation at heating
(see Note), with the outdoor unit evaporation temperature higher than 55 ºC and the compressor-top temperature
higher than 95 ºC.
No
Yes
Y52C turns ON at
operation startup?
Compressor
operates?
No
Yes
Check DIP-IPM
connector wiring
Check the temperature of the following places with the remote control switch in checking mode.
Check the temperature of [1] compressor-top temperature and [2] outdoor unit liquid refrigerant piping. Examine the
cause and address the problem if the measurements surpass the present temperature (See note)
[1]Compressor-top temperature. Preset temperature 95 ºC
[2]Indoor unit liquid refrigerant piping temperature. Preset temperature 55 ºC
Voltage between pins 1
and 3 of DIP-IPM
connector PCN401
approx 0V at operation
startup?
No
Protection device
remains activated?
No
PCN401 correctly
connected?
Faulty DIP-IPM
Does Y52C re-
mains ON for more
than three seconds?
No
Yes
Yes
Detected
(Approx.
15V)
Outdoor unit evaporation thermistor Top of compressor thermistor
Ambient temperature (ºC)
Thermistor resistance (kΩ)
90
80
70
60
50
40
30
20
10
0
-15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60
74
43
33
26
20
16
12.5
10
8
5.3
3.6
2.5
56
Thermistor resistance (kΩ)
Temperature (ºC)
Thermistor resistance characteristics
R25=200kΩ
B=3920K