Panasonic U-4LE2E5 Service Manual & Test Run Service Manual page 146

4. 3WAY Alarm Codes
3. Mini VRF Alarm Codes
P04 Alarm
Alarm code P04
Alarm meaning High pressure swich is activated.
Alarm conditions The operation of the electronic circuit in the high-pressure switch may short-circuit the terminal depending on the
pressure. A pressure of 3.8 MPa or above will short-circuit the terminal. Once the terminal is short-circuited, it will
remain in that state until the pressure goes below 3.15 MPa.
Probable cause
(1) High-pressure switch failure or wiring connection failure
(2) Failure to open the service valve of the outdoor unit
(3) Difference of characteristics of high-pressure sensor
(4) Clogging of the outdoor heat exchanger during cooling
(5) Air short circuit occurs during cooling.
(6) Failure of the outdoor fan during cooling
(7) Clogging of the air filter in the indoor unit during heating
(8) Air short circuit occurs during heating.
(9) Failure of the indoor fan during heating
(10) Clogging of the refrigerant circuit
(11) Failure of the expansion valve
(12) Too much refrigerant has been charged.
Check (1) High-pressure switch failure or wiring connection failure
(2) Failure to open the service valve of the outdoor unit.
(3) Difference of characteristics of high-pressure sensor
(4) During cooling, check whether the outdoor unit heat exchanger is clogged. Remove any foreign material that
(5) During cooling, check whether an air short blockage has occurred in the outdoor unit. The system is
(6) During cooling, check for outdoor fan failure. Check whether the screws securing the fan are loose and
(7) During heating, check whether the air filters in the indoor unit are clogged. If clogged, clean the filters.
(8) During heating, check whether an air short blockage has occurred in the indoor unit. The system operates
(9) During heating, check for indoor fan failure.
(10) Check whether the refrigerant circuit is clogged. Check that all service valves are closed.
(11) Check for expansion valve failure. Check whether the expansion valves make a clattering sound when the
(12) Check for solenoid valve kit failure. Removing a coil that is on will result in a clicking sound.
(13) Check whether too much refrigerant has been charged. Too much refrigerant has been charged if the
(14) Check whether the wiring from the solenoid valve kit is actually connected to the different indoor unit.
(15)
6
Correction Replace damaged components and correct the amount of charged refrigerant.
Check under the section 6. "Inspection and Characteristics of Parts (1) High-pressure switch".
Check whether the socket of the high-pressure switch is surely inserted into the Outdoor Unit Control PCB.
Check open/closed status of the outdoor unit service valve.
Connect a gauge to the high-pressure outlet and check for changes in the value displayed by the monitoring
software, and for large deviation of the gauge pressure.
prevents ventilation.
operating normally unless the temperature around the outdoor unit is excessively high.
whether the fan connector in the outdoor unit PCB is properly connected.
normally unless the temperature around the indoor unit is excessively high.
Check whether welded locations are clogged.
power is reset. Since the expansion valve in the indoor unit is in a location that makes aural inspection
difficult, use an electric means to check. Check that the connector pin of the expansion valve on the PCB
outputs 4 V. In addition, check that the coil resistance of the expansion valve is several tens of Ohm ( Ω ).
Also, removing a coil that is off will not produce such a sound.
sub-cool temperature of the condenser is 15°C or more.
The system is that the multiple indoor units are connected at only one solenoid valve kit and also multiple
remote controllers are connected. Check whether "installation of the common use solenoid valve kit" from a
PC has been made. (Confirmation from the address setting software of a PC)
6 - 18
3WAY SYSTEM
Mini VRF SYSTEM
Trouble Diagnosis
Trouble Diagnosis