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2WAY VRF SYSTEM
Outdoor Unit Repair Procedures
2WAY VRF SYSTEM
Outdoor Unit Repair Procedures
9. Compressor
9-1. Compressor Trouble Diagnosis and Check Methods
Generally, compressor failures can be classified into the following categories.
(1) Mechanical trouble →
(1) Motor →
Min. 300 MΩ
(2) Compressor → Min. 100 MΩ (servicing part)
(3)
* Minimum insulation resistance as required by generally accepted requirements is 1 MΩ.
Unit →
Min. 10 MΩ (This is due to the presence of refrigerant, which decreases the
insulation resistance.)
(A) Locking (intrusion of foreign objects, galling, etc.)
(B) Pressure rise failure (damaged valve, seal, bearing, or other component)
(C) Noise (damaged stator rotor, valve, or other component)
(2) Electrical trouble → (A) Coil burning
(B) Open circuit
(C) Insulation failure
(D) Short circuit
Trouble diagnosis is based on the following remote controller displays:
Reference:
Reference: Symptoms of motor burning
1. Ground fault results in breaker operation.
2. Short circuit results in different coil resistance at different phases.
3. Open circuit
Insulation resistance (Use a DC 500 V insulation resistance meter and measure the insulation resistance
between the electrified and non-electrified parts.)
[P16] [P29] : Compressor 1: INV compressor 1, right side when viewed from front
[P19] [P26] : Compressor 2: INV compressor 2, left side when viewed from front
A judgment is made based on factors that include the following: coil resistance (varies depending on the compressor),
insulation resistance, current, leakage breaker operation, oil and refrigerant fouling, odor, pressure, and noise.
NO
NO
NO
YES
YES
YES
Is there burning of the failed
compressor motor?
Go to “9-2-1. Replacing only the
failed compressor.”
Follow the instructions in
“2. Discharging Compressor Oil”
and drain the oil from the failed
compressor. Then inspect.
Go to “9-2-2. Replacing all
compressors in a failed unit.”
Follow the instructions in
“9-2-4. Dry core cleaning” and
perform dry core cleaning of the
failed outdoor unit.
Is the color
phase 4.0 or above, or is a
sharp odor present?
JUDGMENT START
Follow the instructions in “2. Discharging Compressor
Oil” and drain the oil from all compressors in the same
system. Then inspect.
Follow the instructions in “9-2-4. Dry core cleaning”
and perform dry core cleaning of all outdoor units.
Go to “9-2-3. Replacing all compressors in a system.”
Are there 2
or more outdoor units
wherethe compressor oil color phase is 4.0 or
higher or where a sharp odor is
present?
9. Compressor
2WAY VRF SYSTEM
Outdoor Unit Repair Procedures
(1) If backup operation is required, follow the instructions in “3. Backup Operation” and engage backup operation.
(2) Follow the instructions in “9-3. Removing and Installing Compressors” and replace the failed compressor.
(3) Fully close the high- and low-pressure gauge valves on the manifold gauge, then stop the vacuum pump.
(5) Open the valve on the refrigerant recovery cylinder and the high-pressure gauge valve on the manifold gauge
to charge with refrigerant.
At this time, the low-pressure gauge valve on the manifold gauge remains fully closed.
(6) When charging has been completed with an amount of new refrigerant equal to the amount of recovered
refrigerant, or when charging with the same amount of new refrigerant has not been completed but no more
refrigerant will enter the unit, fully close the high-pressure gauge valve on the manifold gauge.
Next, turn the power OFF at the repaired outdoor unit, then remove the short circuit at the AP pin (CN24).
Finally, fully open all valves on the gas 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 operation
recovery.
(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 in “4-2-1.
Cooling operation (for all units)”, open the low-pressure gauge valve on the manifold gauge and charge with
the designated amount of refrigerant.
(9) Fully close the low-pressure gauge valves on the manifold gauge, follow the instructions in “7. Charging
Compressor Oil,” and charge with oil if necessary.
(10) Remove the manifold gauge.
(4) Disconnect the manifold gauge from vacuum pump.
Connect the manifold gauge to the cylinder where the refrigerant was recovered.
At this time, be careful that air does not enter the tubing.
If the recovered refrigerant becomes mixed with another refrigerant or another gas
(such as nitrogen or air), do not use the recovered refrigerant for charging. Charge
with the designated amount of new refrigerant.
CAUTION
When charging with liquid refrigerant, add refrigerant a little at a time in order to prevent
liquid back-flow.
CAUTION
The connecting port employs a Schrader-type push-to-release valve. When disconnecting
the hose, pressure will be applied from the refrigerant in the outdoor unit.
CAUTION
9. Compressor
9-2. Replacing the Compressor(s)
9-2-1. Replacing only the failed compressor
SM830237-07_北米向け2WAY_VRF.indb 27
18/06/18 18:48:18