Panasonic U-72MF1U9, Service Manual

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Trouble Diagnosis
3. W-3WAY VRF Alarm Codes
1
2
3
4
5
6
7
8
H07 Alarm
Alarm code H07
Alarm meaning No-oil alarm
Alarm conditions This alarm occurs when oil does not fl ow for a specifi ed amount of time in tubing where oil
fl ow constantly. (The presence of oil is detected by a temperature sensor.)
Judgment method:
Tcal (calculated by the formula below from the oil temperature) is compared with the discharge
temperature. If Tcal is higher than the discharge temperature then oil is judged to be present.
If Tcal is lower than the discharge temperature, oil is judged to be not present.
Tcal={(0.0254 · T_oil · LP 2 +0.0298 · T_oil · LP +0.8842 · T_oil –2.9953 · LP 2 –11.091 · LP
+436.94)
+2.9953 · HP
2
+11.091 · HP –436.94}/(0.0254 · HP
2
+0.0298 · HP +0.8842)
Probable cause Insuffi cient amount of oil in the system
(1) The length of system tubing exceeds the allowable tubing length.
(2) The difference in height between system units exceeds the allowable value.
(3) A large amount of oil was drained when a compressor was replaced.
(4) Oil has accumulated in a stopped outdoor unit and has not returned, as a result of refrigerant
circuit clogging or valve leakage at the stopped outdoor unit.
(5) A valve (ORVR, BALV, BPB) in the oil circuit has malfunctioned, or there is clogging of the
circuit (capillaries) which returns oil from the oil separator to the compressor.
(6) If an excessive amount or liquid returns to the compressor, oil foaming may increase oil
discharge. The same occurs when the refrigerant proportion in the compressor is high at start,
due to an open circuit in the crank case heater.
(7) Oil sensor disconnected or open circuit
Check (1) Check the tubing length and height differences.
(2) Check the operation of system circuit valves.
(3) Check that there is not an excessive amount of liquid return. (Check that there is no
mechanical valve leakage.)
(4) Check the crank case heater (wintertime).
(5) Check that the oil sensor is not disconnected, and that the circuit is not open.
Correction (1) If insuffi cient oil is a possibility, then charge with additional oil.
(2) If it is clear that a valve failure has occurred, replace the valve.
Example
Notes
➁
These points are calculated from the oil temperature and compared
with the discharge temperature
High pressure
➃
Higher than the discharge
temperature: Oil present
➀
Oil temperature
➂
Lower than the discharge
temperature: No oil
Low pressure
Discharge
temperature
SM830202-00̲3WAY VRF.indb 18 SM830202-00̲3WAY VRF.indb 18 2012/01/30 14:53:03 2012/01/30 14:53:03