Panasonic WU-144MF1U9E 3-Way Service Manual - Page 66

9. Pumping Out Refrigerant from Outdoor Unit 3-WAY VRF SYSTEM Outdoor Unit Repair Procedures 9-1. If Remote Controller (CZ-RTC2) is Used for Maintenance of Outdoor Unit (1) Refer to "4. Backup Operation" and perform backup operation. (2) Connect the manifold gauge valves at the Lo side to the low-pressure outlet port of the outdoor unit to be repaired. Also connect the refrigerant recovery cylinder to any one of the normal outdoor units at the liquid line service port (Schrader-type push-to-release valve). Perform the connection work quickly so that no air is allowed to enter. (Fig. 2-20) * Connecting the refrigerant recovery cylinder is done to prevent pressure from rising excessively during backup operation by recovering the refrigerant from the outdoor unit to be repaired. (Measure the weight of the refrigerant and cylinder itself beforehand and provide sufficient safety measures, such as installing a high-pressure cutout in the circuit.) CAUTION The hoses may be subject to internal pressure from the refrigerant inside the outdoor unit. Check that the manifold gauge valves are fully closed beforehand. A Schrader-type push-to-release valve is provided at each connection port. 2 (3) Connect the outdoor unit maintenance remote controller to the RC connector (CN006) (3P) (BLU) on the outdoor unit control PCB of the outdoor unit to be repaired. Then start a test run of all units. (Press and hold the (CHECK) button for 4 seconds.) (4) Press the (MODE) button and change to heating operation. CAUTION Even if the mode that is originally displayed is "Heat," be sure to press the (MODE) button once or more to change to heating operation. (Pressing the (MODE) button ensures that heating/cooling operation is not mixed and that all units are operating in either Heating or Cooling mode.) (5) Use the outdoor unit maintenance remote controller to check the operating status of the indoor units. Check that all units are operating in Heating mode. For details concerning operation of the outdoor unit maintenance remote controller, refer to the "Outdoor unit maintenance remote controller" item. CAUTION With the 3-way valve, it is difficult to determine whether operation is heating or cooling by touching the tubing. (6) Close the suction tube and balance tube on the outdoor unit to be repaired. Then slowly close the liquid tube service valve. (7) When the low pressure at the outdoor unit to be repaired reaches 72.5 psi or below, press the ON/OFF button on the outdoor unit maintenance remote controller to stop all the units. Then immediately fully close the discharge tube valve on that outdoor unit. CAUTION While closing the valves, the rise in discharge temperature or another factor may cause a protective device to activate, stopping the operation of the outdoor unit. If this occurs, immediately fully close the discharge tube valve on the outdoor unit to be repaired. (8) Connect the high-pressure gauge side of the manifold gauge to the high-pressure outlet port on the outdoor unit to be repaired, and connect the manifold gauge to the refrigerant recovery device. Be sure that no air enters the tubing at this time. (9) Short-circuit the vacuum application pin on the outdoor unit control PCB of the unit to be repaired. Then turn ON the outdoor unit power. CAUTION When the vacuum application pin is short-circuited and the power is turned ON, all solenoid valves in the outdoor unit are forced open, allowing the refrigerant to be recovered from all tubes which are separated by solenoid valves. If this work is not performed, it will not be possible to recover all of the refrigerant at the refrigerant recovery device. Be sure to perform this step. (10) Open both Hi- and Lo-side valves on the manifold gauge valves, and recover the refrigerant remaining in the outdoor unit. After that, measure the amount of recovered refrigerant. NOTE To determine the completion of refrigerant recovery, follow the instructions that came with the refrigerant recovery unit. 2 - 20