Symptom: Thermostat In Off Continues Or Cycles Off & On Too Frequently - Panasonic U-8MF2E8 Service Manual

8. Symptom: Thermostat in OFF continues or
1. How to detect abnormality
• Abnormality does not occur. Protective function can be checked when the outdoor maintenance remote controller is
connected.
2. Error Diagnosis
1 Indoor control
PC board
1-1
1-2
1-3
1-4
1-5 EXCT(demand control) is applied.
2 Outdoor
control
2-1
PC board
2-2
2-3
5
2-4 DEMAND is applied.
3 Control
3-1
equipment
4 System
4-1
4-2 During defrosting operation
4-3 Service valve of outdoor unit is closed.
4-4 Outdoor unit PC board failure → Replacement
According to the type of models, the indoor sensors will not be supplied in some cases.
According to the type of models, the outdoor DEMAND will not be supplied in some cases.
When LINE Checker is used, the temperature sensors can be observed (display, record) simultaneously.
According to some areas, some of the models are unreleased.
cycles OFF & ON too frequently
Setting temperature reaches the level set ON thermostat.
Setting temperature is too low in heating mode and too high
in cooling and dry mode.
Check if the sensors are connected correctly.
Are all connection made properly?
Room temp. (TA) in yellow, heat exchanger (E1) in red,
heat exchanger (E3) in brown, air outlet (BL) in green
DISP (display mode) is applied.
With a thermostat OFF in heating mode, wind speed
(item code 05) is out of range 0 - 6. (Use Simple Setting
Function on standard timer remote controller.)
Outdoor unit and protective function of a system are operating.
(Connect outdoor maintenance remote controller to RC socket
on outdoor unit main control PC board and check alarm
messages.)
Discharge temperature is over 80°C in stop mode and does not
decrease. (Connect outdoor maintenance remote controller to
RC socket on outdoor unit main control PC board and check
alarm messages.)
Demand value always stays low.
(Excluding -1 (unlimited))(Connect outdoor maintenance remote
controller to RC socket on outdoor unit main control PC board
and check alarm messages.)
Demand setting is made by control units (P-AIMS, Seri-Para I/O
unit for outdoor unit, Seri-Para I/O each indoor unit.)
When operating in cooling (including auto cooling & heating)
and dry mode, lowest temp. of indoor E1 and E3 sensor is
less than 2°C (under anti-freeze control).
5 - 30
3WAY SYSTEM
Trouble Diagnosis
Adjust setting
Yes
temperature
No 1-2
Yes Connect correctly
No 1-3
Yes Turn OFF(OPEN)
No 1-4
Yes Choose one of 0 to 6
No 1-5
Yes Turn OFF(OPEN)
No 2-1
Yes See operational status
No 2-2
Replace discharge
Yes
temperature sensor
No 2-3
Yes Increase values
No 2-4
Yes Turn OFF (OPEN)
No 3-1
Yes Turn OFF
No 4-1
Wait until more than
Yes
2°C reaches
No 4-2
Wait for a few minutes
Yes
to 10 minutes or so
No 4-3
Yes Open service valve
No 4-4