Panasonic U-72MF2U9 Service Manual

Also see for U-120MF2U9: Installation instructions Operating instructions Installation instructions Technical data

Contents

2 - 251234567893WAY VRF SYSTEMOutdoor Unit Repair Procedures9. Compressor2WAY VRF SYSTEMOutdoor Unit Repair Procedures9. Compressor9-2-2. Replacing all compressors in a failed unit(1) Follow the instructions in “2. Discharging Compressor Oil” and drain the oil from the oil separator in the failedunit. Measure the amount of drained oil.(2) If backup operation is required, follow the instructions in “3. Backup Operation” and engage backup operation.(3) Follow the instructions in “9-3. Removing and Installing Compressors” and replace all compressors in thefailed unit.(4) Fully close the high- and low-pressure gauge valves on the manifold gauge, then stop the vacuum pump.(5) Disconnect the manifold gauge from the vacuum pump. Connect the manifold gauge to the refrigerant cylinder.At this time, be careful that air does not enter the tube.(6) Open the valve on the refrigerant cylinder, and open the high-pressure gauge valve on the manifold gauge (withthe low-pressure gauge valve closed). When charging has been completed with an amount of new refrigerantequal to the amount of recovered refrigerant, or when charging with the same amount of new refrigerant hasnot been completed but no more refrigerant will enter the unit, fully close the high-pressure gauge valve on themanifold gauge. Next, turn the power OFF at the repaired outdoor unit, then remove the short circuit at the APpin (CN24).Finally, fully open all valves on the suction tube, discharge tube, liquid tube, and balance tube.However, leave the balance tube fully closed if only a single outdoor unit is installed.(7) If backup operation was engaged, follow the instructions in “3. Backup Operation” and perform backup operationrecovery.(8) If charging with an amount of new refrigerant equal to the amount of recovered refrigerant was not possible,fully close the high-pressure gauge valve on the manifold gauge. Then, while the unit is operating accordingto “4-2-1. Cooling operation (for all units)”, open the low-pressure gauge valve on the manifold gauge andcharge with the designated amount of refrigerant.(9) Fully close the low-pressure gauge valves on the manifold gauge, follow the instructions in “7. ChargingCompressor Oil”, and charge with the necessary amount of oil. Also add an amount of oil that is equivalent tothe amount that was drained from the oil separator.(10) Remove the manifold gauge.(11) Follow the instructions in “9-2-4. Dry core cleaning” and perform dry core cleaning of the outdoor unit that failed.Do not reuse the recovered refrigerant. Use a refrigerant cylinder that contains newrefrigerant.CAUTIONWhen charging with liquid refrigerant, add refrigerant a little at a time in order to preventliquid back-flow.CAUTIONThe connecting port employs a Schrader-type push-to-release valve. When disconnectingthe hose, pressure will be applied from the refrigerant in the outdoor unit.CAUTION