Hitachi UTOPIA RAS-4HVRP2E - Page 285

10 Troubleshooting
Troubleshooting procedure
SMGB0136 rev.0 - 07/2021
283
10
Alarm code
43
Activation of Pressure Ratio Decrease Protection
• Thealarmcodeisashedonthe7-segmentdisplayoftheoutdoorunit.
• The alarm code is displayed on the wired controller of the indoor unit.
Ifthepressureratioɛ
*1)
is less than 1.5 for a minute, the compressor stops. It automatically restarts after three minutes. If
this occurs again twice in the next 30 minutes, this alarm code is displayed.
*1)
PressureRatioɛ=(Pd[MPa]+0.1)/(Ps[MPa]+0.1)
Pd: high pressure (discharge pressure) Ps: low pressure (suction pressure)
Phenomenon
Cause
Check Item
Action (Turn OFF
Main Switch)
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Does inverter operate?
Does compressor operate?
Check inverter
Check compressor and power wiring
Is 4-way valve stopped at middle
position?
Are high pressure sensor and low
pressure sensor normal?
Is there refrigerant leakage from
solenoid valve (SVA)?
Check that indoor/outdoor inlet air
temperature is not too low
Replace 4-way valve if faulty
Replace high pressure sensor or low
pressure sensor if faulty
Replace solenoid valve (SVA) if faulty
Excessively Low
Pressure Ratio
Inverter is not operating
Compressor is not operating
Valve Stoppage at Middle Position
of 4-Way Valve
Abnormality of High or Low Pressure
Sensor
Excessively Low Indoor Inlet Air
Temperature
Leakage from Solenoid Valve (SVA)
Check inverter
Repair faulty part
Check compressor
Measure suction pipe
temperature of 4-way valve
Check connector for Outdoor
Unit, power supply and
pressure indication
Check Indoor Unit and
Outdoor Unit air temp.
thermistor
Check Solenoid Valve
Replace compressor if faulty
Replace 4-way valve if faulty
Replace sensor if faulty
Replace thermistor if faulty
Replace SVA if there is
leakage