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2
Mini VRF SYSTEM
Outdoor Unit Repair Procedures
3. Recovering Refrigerant
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
3-2-3. Refrigerant recovery procedures (B): for indoor unit with no ball valve
Refrigerant in all indoor units and the refrigerant tubing circuit must be pumped into the outdoor unit (referred to as
“pump down”). The maximum refrigerant storage capacity per a single outdoor unit is approx. 3.5 k
“pump down”). The maximum refrigerant storage capacity per a single outdoor unit is approx. 3.5 k
g. Thus, in order
to collect all refrigerant from the system, a separate refrigerant recovery unit is necessary. Follow these procedures
to correctly perform pump down.
to correctly perform pump down.
Using hoses, connect the manifold gauge valves to both the high-pressure and low-pressure outlet ports of
the outdoor unit to be pumped down. Quickly connect each part to prevent air from entering the tubing.
the outdoor unit to be pumped down. Quickly connect each part to prevent air from entering the tubing.
After running the unit in Cooling mode for about 5 minutes, fully close the liquid line valve of the outdoor unit to
be pumped down.
be pumped down.
When the high-pressure gauge reading shows 3.80 MPa or more (or the low-pressure gauge reading falls to 0.5
MPa or less), pull out the EXL2 connector (3P) (YEL) (CN-RC) on the control PCB of the outdoor unit, then
immediately close the gas line service valve.
* As soon as the EXL2 connector is pulled out, F24 alarm (abnormal sensor) immediately turns on and the
outdoor unit stops.
MPa or less), pull out the EXL2 connector (3P) (YEL) (CN-RC) on the control PCB of the outdoor unit, then
immediately close the gas line service valve.
* As soon as the EXL2 connector is pulled out, F24 alarm (abnormal sensor) immediately turns on and the
outdoor unit stops.
When pulling out the EXL2 connector, be sure to grasp the connector securely
with your fingers and never pull it directly by its wires. When any other connector
except the EXL2 is disconnected, the outdoor unit will not stop. Be sure to pull
out only the EXL2 connector as described.
with your fingers and never pull it directly by its wires. When any other connector
except the EXL2 is disconnected, the outdoor unit will not stop. Be sure to pull
out only the EXL2 connector as described.
Turn off power to all equipment in the system. Then pull out the RC1 connector (4P) (BLU) (CN006) on the
outdoor control PCB in the outdoor unit for which pump down has been completed.
outdoor control PCB in the outdoor unit for which pump down has been completed.
Turn on power for all equipment in the system and let the outdoor unit run in Cooling mode.
* Because the test run pins on the outdoor control PCB of the unit have been short-circuited, all units start
Cooling mode operation 3 minutes after power ON.
Cooling mode operation 3 minutes after power ON.
Using hoses with Schrader-type, push-to-release valves, connect the manifold gauge valves to the gas line
service port and the liquid line service port in the outdoor unit to undergo pump-down. (Fig. 2-5)
service port and the liquid line service port in the outdoor unit to undergo pump-down. (Fig. 2-5)
Remaining refrigerant in the system may cause internal pressure. Check that each
valve on the manifold gauge is tightly closed. A Schrader-type, push-to-release
valve is provided for each connection port.
valve on the manifold gauge is tightly closed. A Schrader-type, push-to-release
valve is provided for each connection port.
Use hoses to connect the manifold gauge valves, refrigerant recovery unit, and refrigerant recovery cylinder.
Quickly connect each part to prevent air from entering the tubing.
Quickly connect each part to prevent air from entering the tubing.
Recover remaining refrigerant from
the inter-unit tubing and indoor units
using the refrigerant recovery unit.
the inter-unit tubing and indoor units
using the refrigerant recovery unit.
To determine the completion of
refrigerant recovery, follow the
instructions that came with the
refrigerant recovery unit.
refrigerant recovery, follow the
instructions that came with the
refrigerant recovery unit.
NOTE
CAUTION
CAUTION
Fig. 2-5
Refrigerant recovery cylinder
Refrigerant
recovery unit
recovery unit
Manifold
gauge
Low-pressure outlet port
(For ø7.94 mm connector)
(For ø7.94 mm connector)
Lo
Hi
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2
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.
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.
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.
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)
(For ø7.94 mm connector)
Lo
Hi
High-pressure outlet port
(For ø7.94 mm connector)
(For ø7.94 mm connector)
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2
Mini VRF SYSTEM
Outdoor Unit Repair Procedures
5. Evacuating System
(1)
(2)
(3)
(4)
(5)
(6)
This procedure is carried out to ensure there is no remaining refrigerant or other gases (nitrogen, etc.) in the
repaired outdoor unit and tubing.
repaired outdoor unit and tubing.
5-1. Evacuating Repaired Outdoor Unit
Check that each service valve of the gas line, and the liquid line in the outdoor unit are fully closed.
* If the AP pins (CN-AP) on the outdoor control PCB have already been short-circuited, steps (2) and (5) are
not necessary.
* If the AP pins (CN-AP) on the outdoor control PCB have already been short-circuited, steps (2) and (5) are
not necessary.
Turn off power to the outdoor unit to be evacuated.
Connect the manifold gauge valves to the high- and low-pressure sensor outlets of the outdoor unit.
Connect the manifold gauge valves to the vacuum pump.
Short-circuit the AP pins on the outdoor control PCB and turn on power to the repaired outdoor unit.
By short-circuiting the AP pins and turning on power to the outdoor unit, all
electronic expansion 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.
electronic expansion 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.
To ensure proper evacuation, refer to the operating instructions that came
with the vacuum pump.
with the vacuum pump.
Run the vacuum pump and continue evacuation until the vacuum condition falls to less than –101 kPa
{–755 mmHg, 5 Torr}.
{–755 mmHg, 5 Torr}.
5-2. Evacuating Refrigerant Tubing Between Indoor and Outdoor Units
Refer to the “Installation Instructions” that came with the outdoor unit.
CAUTION
CAUTION
Vacuum pump
Fig. 2-7
Manifold
gauge
Low-pressure outlet port
(For ø7.94 mm connector)
(For ø7.94 mm connector)
Lo
Hi
High-pressure outlet port
(For ø7.94 mm connector)
(For ø7.94 mm connector)
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2
Mini VRF SYSTEM
Outdoor Unit Repair Procedures
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
Required equipment and tools: Jumper wire with clips, adjustable wrench, set of manifold gauge valves, vacuum
pump, refrigerant recovery unit, pre-purged refrigerant cylinder for recovery, and
hex wrench (4 mm for liquid tube and 5 mm for gas tube).
hex wrench (4 mm for liquid tube and 5 mm for gas tube).
This procedure is used to move refrigerant of the faulty outdoor unit (except compressor) into indoor units, and
refrigerant tubing.
refrigerant tubing.
Connect the manifold gauge valves at the Lo-side to the low-pressure sensor outlet 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, with push-to-release valve). Perform the connection work quickly so that no air is
allowed to enter.
repaired. Also connect the refrigerant recovery cylinder to any one of the normal outdoor units at the liquid line
service port (Schrader type, with push-to-release valve). Perform the connection work quickly so that no air is
allowed to enter.
* Connecting the refrigerant recovery cylinder is done to prevent pressure from rising excessively during the
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.)
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.)
Short-circuit the TEST pin (CN-TEST) on the outdoor control PCB of the main unit.
After operating the unit for a while, judge whether it is running in Cooling or Heating mode by touching the gas
line cautiously with your fingers. If it is running in Cooling mode, follow the instructions given in (4) through (6).
line cautiously with your fingers. If it is running in Cooling mode, follow the instructions given in (4) through (6).
* The gas line reaches a low temperature (under 20°C) during cooling operation, and a high temperature (over
60°C) during heating operation.
60°C) during heating operation.
Be careful when testing the temperature of the gas line with your fingers, because
the tubing becomes very hot (about 60°C) when Heating mode is used.
the tubing becomes very hot (about 60°C) when Heating mode is used.
If the unit is in Cooling mode, temporarily release the short-circuit across the test run pins on the outdoor
control PCB of the unit. Then, short-circuit the STOP pin (CN-STOP) to stop operation of the unit.
Short-circuit the MODE pin (CN-MODE) on the outdoor control PCB of the main unit.
* The 4-way valve will not change at this moment; rather, it changes just before start of operation. (It is difficult
to confirm the change by listening for the sound.)
to confirm the change by listening for the sound.)
Short-circuit the TEST pin (CN-TEST) on the outdoor control PCB of the unit. Let the unit operate for a while, then
check if it is in Heating mode by cautiously touching the gas line.
check if it is in Heating mode by cautiously touching the gas line.
Slowly close the liquid line service valve of the outdoor unit to be repaired.
When the low-pressure gauge reading shows 0.5 MPa or less, pull out the EXL2 connector (3P) (YEL)
(CN-RC) on the control PCB of the outdoor unit to be repaired and then fully close the gas line service valve
immediately.
(CN-RC) on the control PCB of the outdoor unit to be repaired and then fully close the gas line service valve
immediately.
* By pulling out the EXL2 connector, all outdoor units stop immediately.
While closing the valve, the outdoor unit may suddenly stop. This is because a
protective function, such as for discharge temperature, is working. In this case
also, fully close the gas line service valve immediately.
protective function, such as for discharge temperature, is working. In this case
also, fully close the gas line service valve immediately.
Connect the high-pressure sensor outlet of the outdoor unit to be repaired to the manifold gauge valves at the
Hi-side. Also connect the manifold gauge valves to the refrigerant recovery unit. Perform the connection work
quickly so that no air is allowed to enter.
Hi-side. Also connect the manifold gauge valves to the refrigerant recovery unit. Perform the connection work
quickly so that no air is allowed to enter.
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.
outdoor unit. After that, measure the amount of recovered refrigerant.
CAUTION
CAUTION
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.
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.
6. Pumping Out Refrigerant from Outdoor Unit
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