P18 Bypass Valve Error - Panasonic 2WAY Multi Technical & Service Manual

P18 Bypass Valve Error

Error detection method
• A warning is output if it is determined that the outdoor unit needs a bypass valve inspection.
• In practical terms, what happens is that each time there is a small difference (
high and low pressure (
suspected error counter increments, and the data is recorded as "pre-trip" warning history data. After the
counter reaches 5, a warning is output on the next complete combustion startup.
Understanding the warning history
The latest P18 data in the warning history is issued immediately after a complete combustion startup. It is not
the data used for detecting the error. If a pre-trip error was detected (when the suspected error counter reaches 5),
that data is the next more recent P18 data.
Troubleshooting
1 ● Bypass valve inspection
Bypass During operation, use the No. 4 test mode "v_close" (close
1-1
valve valve) to close the bypass valve (step 0). Check whether
inspection refrigerant is not leaking on entering the bypass.
● Bypass valve inspection
After completing the above inspections, stop the engine and
1-2 use No.4 test mode "v_open" (open valve) to open the bypass
to check that the bypass valve operates normally despite the
fl uctuations in tube temperature around the bypass valve.
● Outdoor main board inspection
1-3 Is there approximately 12 V of pressure at bypass valve output
ports 5 (+) and 1 to 4 (-) when the power is on?
● Electric valve coil inspection
1-4 Are the resistance values for electric valve connectors 5 and
1 to 4 about 40 Ω?
2
2-1 Is the outdoor unit a 3-WAY MULTI-device?
Four-way
valve
Inspect
2-2 Is the four-way valve free from leakage?
outdoor
solenoid
valves
Are the outdoor solenoid valves (discharge valves 1 and 2,
and suction valves 1 and 2) free from leakage?
2-3
* Suction valve 1 closes when current fl ows through it (other
solenoid valve remain open)
3
● Liquid valve inspection
Liquid valve
3-1 Any refrigerant leaks past the liquid valve when the liquid
inspection
valve is completely closed (step 0)?
4 Is the operation mode heating?
Expansion * Note: If you are operating with a 3WAY MULTI, try 4-2 and
4-1
valve
inspection
● Outdoor expansion valve inspection
4-2 Check that there are no refrigerant leaks past the outdoor
expansion valve when the engine is stopped in heating mode.
● Indoor electric valve inspection
Stop the indoor unit during cooling operation (multiple indoor
4-3 unit operation, indoor electric valve opening = 20 steps) and
check to make sure there is no coolant leakage beyond the
indoor electric valve.
5
Pressure Pressure sensor inspection (refer to the section on F16 for the
5-1
sensor inspection procedure)
inspection
● For work procedure for replacing outdoor main board, see "5. Reference Document".
P = high pressure - low pressure) 90 seconds after stopping the engine stops, a
4-3 before shutting down the engine as this might be
due to cooling and heating mixed operation.
IV–94
P ≤ 0.1 MPa) between the
OK 1-2
Replace the bypass
NG
valve unit
OK 2-1
NG 1-3
Yes 1-4
Replace outdoor main
No
board
Replace the bypass
Yes
valve unit
Replace the bypass
No
valve coil
Yes 2-3
No 2-2
OK 3-1
Replace the four-way
NG
valve
OK 3-1
Replace the solenoid
NG
valve.
OK 4-1
Replace the liquid valve
NG
unit
Yes 4-2
No 4-3
OK 5-1
Replace the outdoor
NG
expansion valve unit
OK 5-1
Replace indoor electric
NG
valve unit
Replace outdoor main
OK
board
NG Repair