Pressure Sensor Failure; Way Valve Failure [L18] - Panasonic U-4LE1E5 Service Manual

11. Current Protection

12. Pressure Sensor Failure

13. 4-Way Valve Failure [L18]

11-2. Inverter Compressor
Alarm
P16
1
P29
H31
The inverter current values include primary current and secondary current.
Alarm judgment uses both of these current values. However, in general the secondary
current is higher than the primary current.
11-3. CT Circuit Detection Failure
Compressor 1
(inverter compressor)
If the operating frequency of the inverter compressor is low, the current value is also low.
As a result, this alarm is detected only when the compressor is stopped.

12. Pressure Sensor Failure

This system includes a high-pressure sensor.
12-1. High-Pressure Sensor Failure
Connector disconnection or displacement failure is judged according to the relationship between the high-pressure
sensor temperature, which is detected by the high-pressure sensor, and the various temperature thermistors.
However, if the pressure rises suddenly, a high-pressure sensor failure warning may be judged before the high-
pressure sensor activates. Therefore check the following before determining that a pressure sensor failure has
occurred:
• Has the service valve been left open?
• Is there a blocked circuit?
• Is there leakage of refrigerant into stopped outdoor units?
Also check the difference between the high-pressure pressure as measured by a manifold gauge and the pressure
as detected by the pressure sensor.
Alarm
F16

13. 4-Way Valve Failure [L18]

When a 4-way valve coil failure, coil disconnection or similar failure occurs, a judgment is made automatically from
the operating conditions, and an alarm is output.
Description
Occurs when overcurrent (32.5 A) is detected during normal
operation.
Occurs when a missing phase or overcurrent (48 A) is detected
when the inverter compressor starts.
Occurs when the HIC detects overcurrent (75 A), and when an
abnormal temperature (150°C) is reached.
Alarm
Occurs when an open circuit is detected in the inverter
H03
compressor CT circuit.
Description
High-pressure sensor failure
Description
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