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2WAY VRF SYSTEM
Outdoor Unit Repair Procedures
2WAY VRF SYSTEM
Outdoor Unit Repair Procedures
5. Checking for Leakage After Repair
(1) Check that all service valves for gas tubes, liquid tube, and balance tube in the repaired outdoor unit (units
necessary to carry out the pressurized leak check) are fully closed.
(2) Connect the manifold gauge valves to the high- and low-pressure outlet ports of the outdoor unit.
(3) Feed nitrogen gas into the circuit until 484 psi (3.34 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 pin (CN24) on the outdoor
unit control PCB, turn on power to run the outdoor unit, then resume feeding nitrogen.
(4) Apply soapy water to the repaired part (such as a newly brazed 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 pin
(CN24).
Again feed nitrogen gas to obtain a system pressure of 484 psi (3.34 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.
After completing repair of the outdoor unit, carry out the following leakage check.
5-1. Pressure Check for Leakage of Outdoor Unit
Refer to the “Installation Instructions” that came with the outdoor unit.
5-2. Checking for Leakage in Refrigerant Tubing Between Indoor and Outdoor Units
Lo
Hi
Manifold
gauge
Fig. 6-b
Fig. 6-a
High-pressure outlet port
(for ø5/16” (ø7.94mm)-dia connector)
Low-pressure outlet port
(for ø5/16” (ø7.94mm)-dia connector)
Liquid tube service port
(for ø5/16” (ø7.94mm)-dia connector)
Gas tube service port
(for ø5/16” (ø7.94mm)-dia connector)
High-pressure outlet port
(for ø5/16” (ø7.94mm)-dia connector)
Low-pressure outlet port
(for ø5/16” (ø7.94mm)-dia connector)
Liquid tube service port
(for ø5/16” (ø7.94mm)-dia connector)
Gas tube service port
(for ø5/16” (ø7.94mm)-dia connector)
Type: 72, 96
Type: 120, 144
Lo
Hi
Manifold
gauge
Nitrogen gas
Nitrogen gas
6. Evacuating System
2WAY VRF SYSTEM
Outdoor Unit Repair Procedures
6. Evacuating System
Vacuum pump
(1) Check that each service valve of the gas tubes, liquid tube, and balance tube in the outdoor unit are fully closed.
(4) Turn off power to the repaired outdoor unit and short-circuit the AP pin (CN24) on the outdoor control PCB.
(2) Connect the manifold gauge valves to the high-pressure and low-pressure sensor outlets of the outdoor unit.
(Figs. 7-a, 7-b)
(3) Connect the manifold gauge valves to the vacuum pump.
* If the AP pin (CN24) on the outdoor control PCB have already been short-circuited, step (4) is not necessary.
(5) Turn the power ON at the outdoor unit where vacuum will be applied. Then run the vacuum pump and continue
evacuation until the vacuum condition falls to less than –14.7 psig { -101 kPa, 5 Torr }.
By short-circuiting the AP pin (CN24) and turning on power to the outdoor unit, all
electronic valves in the outdoor unit are forcibly opened and any remaining nitrogen
gas can be recovered. Failure to perform this procedure may result in nitrogen
gas remaining in the refrigerant circuit and causing operating problems. Therefore,
never skip this step.
CAUTION
To ensure proper evacuation, refer to the operating instructions that came with the
vacuum pump.
CAUTION
Fig. 7-b
Fig. 7-a
Type: 72, 96
Type: 120, 144
6-1. Evacuating Repaired Outdoor Unit
Refer to the “Installation Instructions” that came with the outdoor unit.
6-2. Evacuating Refrigerant Tubing Between Indoor and Outdoor Units
This procedure is carried out to ensure there is no remaining refrigerant or other gases (nitrogen, etc.) in the
repaired outdoor unit and tubing.
Vacuum pump
Lo
Hi
Manifold
gauge
High-pressure outlet port
(for ø5/16” (ø7.94mm)-dia connector)
Low-pressure outlet port
(for ø5/16” (ø7.94mm)-dia connector)
Liquid tube service port
(for ø5/16” (ø7.94mm)-dia connector)
Gas tube service port
(for ø5/16” (ø7.94mm)-dia connector)
High-pressure outlet port
(for ø5/16” (ø7.94mm)-dia connector)
Low-pressure outlet port
(for ø5/16” (ø7.94mm)-dia connector)
Liquid tube service port
(for ø5/16” (ø7.94mm)-dia connector)
Gas tube service port
(for ø5/16” (ø7.94mm)-dia connector)
Lo
Hi
Manifold
gauge
SM830237-07_北米向け2WAY_VRF.indb 15
18/06/18 18:48:13
