Cooling Overload (High Pressure Switch Will Be Activated) For Ras-(2-2.5)Hvnp1 And Ras-3Hvnc1 - Hitachi RAS-(3-6)HVNC1(E) Service Manual

8 Troubleshooting
41
Alarm code
- Abnormality indication will appear when the protection device is activated during compressor operation at cooling
(see Note), with the outdoor unit evaporation temperature higher than 55ºC and the compressor-top temperature
higher than 95ºC.
Y52C turns ON at
No
operation startup?
Compressor
operates?
Yes
Does Y52C re-
mains ON for more
than three seconds?
Yes
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
Outdoor unit evaporation thermistor
90
80
74
70
60
56
50
43
40
33
30
26
20
20
10
0
-15 -10 -5 0 5 10
Ambient temperature (ºC)
254
SMGB0087 rev.0 - 12/2013

Cooling Overload (High pressure switch will be activated) for RAS-(2-2.5)HVNP1 and RAS-3HVNC1

Voltage between pins 1
and 3 of DIP-IPM
connector PCN401
approx 0V at operation
startup?
Yes
No
16 12.5
10
8
5.3
3.6
15 20 25 30 35 40 45 50
Detected
(Approx.
15V)
Protection device
No
remains activated?
Top of compressor thermistor
2.5
55 60
Thermistor resistance characteristics
PCN401 correctly
No
connected?
No
Check DIP-IPM
connector wiring
Faulty DIP-IPM
R25=200kΩ
B=3920K
Temperature (ºC)
Yes