Panasonic U-4LE1E5 Service Manual page 120

3. Mini VRF System Alarm Codes
P04 Actuation of High Pressure Switch
1. Error Detection Method
It is judged an error if the internal circuit of the high pressure switch is dead.
The electronic circuitry of the high pressure switch is cut off if the pressure at the pressure sensor port of the high pressure
switch reaches 3.80 MPa. Once it is cut off, it remains cut off until the pressure drops to 3.15 MPa.
• The high pressure switch is malfunctioning.
• Service valve inside the outdoor unit closed
• There is a short air circuit through the outdoor unit's heat exchanger. (when cooling)
• The outdoor unit's fan is broken. (when cooling)
• The outdoor unit's heat exchanger is clogged. (when cooling)
•
There is a short air circuit at the indoor unit. (when heating)
•
The filter of the indoor unit is clogged. (when heating)
•
The fan of the indoor unit is broken or the fan motor is malfunctioning. (when heating)
• The refrigerant circuit is closed and the high pressure is increasing abnormally high.
(solenoid valve or expansion valve not activated, a stuck check valve, etc.)
• Refrigerant overcharged.
• Nitrogen or air contaminated in the refrigerant system
2. Error Diagnosis
1 High
pressure
1-1
switch
1-2
2 Service
valve
2-1
2-2
5
2-3
3 Problem
3-1
around the
heat
exchanger
3-2
3-3
3-4
3-5
The socket of the high pressure switch is securely inserted in the
PC board. The wiring is not opened.
Even if parts near the high pressure switch are shaken quite a lot,
the high pressure cutoff will be activated.
Even if the covering is in good condition, in several cases vibration
has caused wiring inside to open.
Service valve inside the outdoor unit closed
There is an extreme difference in temperature in/out of the service
valve.
Check the flare connection, someone may have forgotten to remove the bonnet.
If there is a problem within the service valve, replace the valve.
While cooling is operating an alarm is occurred.
The intake temperature (ambient temperature) of the outdoor unit's
heat exchanger is above 46°C.
The outdoor unit's heat exchanger is clogged.
Check whether the outdoor unit fan is normal or if the sockets are
firmly pressed onto the plugs on the outdoor PC board, as well as
if any wiring is opened.
Are these checking finished without fail?
While heating is operating an alarm is occurred.
5 - 40
Mini VRF SYSTEM
Trouble Diagnosis
Yes 1-2
Correct connection
No
and/or wiring
Replace the
Yes high pressure
switch (wiring)
No 2-1
Open the service
Yes
valve
No 2-2
Yes 2-3
No 3-1
Yes 3-2
No 3-5
Prevent air short
Yes
circuit
No 3-3
Clean the heat
Yes
exchanger
No 3-4
Yes 4-1
Replace the outdoor
unit fan.
No
Correct connection
and/or wiring
Yes 3-6
No 4-1