Panasonic U-4LE1E5, Service Manual, Page: 38 / 133

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Mini VRF SYSTEM
Outdoor Unit Repair Procedures
4. Checking for Leakage After Repair
(1)
(2)
(3)
(4)
*
4-1. Pressure Check for Leakage of Outdoor Unit
After completing repair of the outdoor unit, carry out the following leakage check.
Check that all service valves for gas line, and liquid line in the repaired outdoor unit are fully closed.
Connect the manifold gauge valves to the high- and low-pressure sensor outlets of the outdoor unit.
Feed nitrogen gas into the circuit until 3.80 MPa pressure is reached. If it is apparent that the nitrogen gas is not
entering the repaired section, interrupt the feeding. Short-circuit the AP pins (CN-AP) on the outdoor unit control
PCB, turn on power to run the outdoor unit, then resume feeding nitrogen.
Apply soapy water to the repaired part (such as a newly welded part), and briefly inspect for any leakage.
If there are any leaks, bubbles will show on the tubing surface.
To continue the air-tight check after the brief leak inspection, turn on power while short-circuiting the AP pins.
Again feed in nitrogen gas to obtain a system pressure of 3.80 MPa. Then measure both the outdoor ambient
temperature and the pressure in the system. Leave the system in this state for 1 full day and night, and again
measure the outdoor ambient temperature and pressure (to determine any reduced values). During the
inspection, it is recommended that an awning or cover be used to shield the unit in case of rain. If no problem
is found, purge all nitrogen from the system.
Nitrogen gas
Fig. 2-6
4-2. Checking for Leakage in Refrigerant Tubing Between Indoor and Outdoor Units
Refer to the “Installation Instructions” that came with the outdoor unit.
Manifold
gauge
Low-pressure outlet port
(For ø7.94 mm connector)
Lo Hi
High-pressure outlet port
(For ø7.94 mm connector)
SM830195-01̲Mini VRF SYS.indb 10 SM830195-01̲Mini VRF SYS.indb 10 2011/12/20 16:31:16 2011/12/20 16:31:16