General Assist Technical Reference

VRF PCB Replacement

Addressing, capacity check and return-to-service procedure
STOP — do not energise a replacement PCB until its settings have been verified.
A replacement VRF PCB is not plug-and-play. Every DIP switch, rotary switch, address, connector and relevant field setting must be recorded from the old PCB and correctly applied to the replacement board.

Why this matters

Incorrect PCB configuration can cause duplicate or missing addresses, incorrect refrigerant-circuit identification, communication errors, incorrect master/slave operation, terminal-resistor faults, failed capacity checks and repeat service attendance.

Before you start

Required equipment and information
✓ Exact installation or service manual for the affected model
✓ Approved replacement PCB with verified part number and revision
✓ Lock-out/tag-out equipment and approved voltage tester
✓ Camera or phone for clear before-and-after photographs
✓ ESD controls and insulated hand tools
Mandatory evidence before removing the old PCB
☐ Wide photograph showing the complete electrical box and cable routing
☐ Close-up photographs showing every DIP and rotary switch position
☐ Clear photographs of all plugs, terminals, earths and wire positions
☐ Written record of IU address, REF address, outdoor address, master/slave and terminal resistor
☐ Original fault code, symptoms and diagnostic basis for PCB replacement

PCB replacement procedure

1. Confirm the component and VRF generation
Record the complete model and serial number. Confirm whether the replacement is an indoor main PCB, outdoor control PCB, inverter PCB, RB unit PCB, signal amplifier or another networked component. Use the exact model manual.
2. Isolate and prove de-energised
Stop the system normally where possible. Isolate every supply feeding the affected component. Apply lock-out/tag-out, prove de-energised and allow the required capacitor discharge time.
3. Record the original configuration
Photograph and write down every switch, address and connector position before disturbing the old PCB. Record all DIP switches, rotary switches, outdoor unit number, master/slave setting, terminal resistor and optional settings.
4. Install the approved replacement PCB
Use ESD precautions. Compare part numbers, software or revision labels and connector identification. Reconnect all plugs and earths fully and ensure no wiring is trapped or under tension.
5. Set all switches and addresses before restoring power
Replicate the old PCB settings exactly, unless a documented engineering instruction requires a change. Confirm the printed ON direction. Never energise a new PCB with unverified factory-default settings.
6. Restore power and verify the network
Refit covers, restore all required indoor and outdoor supplies, and allow the transmission network to initialise. Confirm controller power, transmission wiring and terminal-resistor configuration.
7. Readdress the replaced component
For J-II, V-II and VR-II generations onward, complete the model-specific address-setting procedure after replacing an addressable PCB. Copying the physical switches alone may not complete the repair.
8. Complete the capacity / connection check
Verify the detected indoor-unit quantity and connected-capacity ratio against the site design or known system configuration. Investigate every Err result, missing unit, duplicate address or implausible ratio.
9. Test operation
Complete heating and/or cooling test operation. Confirm stable communication, normal operation of the replaced component and no active or unexplained faults.
10. Document and close the job
Attach before-and-after photographs, switch settings, addressing results, detected indoor count, capacity ratio and test-run outcome. Record any intentional setting change and who authorised it.

Indoor PCB address settings

Where an indoor PCB uses rotary switches, both the indoor-unit address and refrigerant-circuit address must match the removed PCB or approved addressing schedule.

Address switch reference
Indoor-unit addressIU AD ×10 and IU AD ×1Range 0–63
Refrigerant-circuit addressREF AD ×10 and REF AD ×1Range 0–99
Example
Indoor address 23: set IU AD ×10 = 2 and IU AD ×1 = 3.
Refrigerant circuit 07: set REF AD ×10 = 0 and REF AD ×1 = 7.
Addressing rules: addresses must be unique; the REF address must correspond with the correct outdoor system; automatic addressing requirements must be checked in the exact model manual; and manually addressed systems must remain consistent with central-controller or BMS records.

J-X family reference

Applicability warning: The sequences below apply to the published J-IVS / J-IV / J-IVL commissioning process. Other generations may use different menus and switch combinations. Always confirm the exact model manual.

Automatic indoor addressing — F3-11 (not requirement most of the time as indoors are already set)

1. Press MODE / EXIT once; F1 flashes.
2. Press SELECT until F3 displays, then press ENTER.
3. Select 11 and hold ENTER for at least 3 seconds. “run” displays.
4. LED105 shows successfully addressed units; LED104 shows failed units.
5. Resolve failures, repeat the process, then press ENTER when all units succeed.
6. Power reset all indoor units for 2 minutes.

Indoor capacity / connection check — F3-12 (required)

1. Enter F3 as above.
2. Select 12 and hold ENTER for at least 3 seconds. “run” displays.
3. Read the detected indoor-unit quantity and compare it with the site.
4. Press SELECT to display the connected-capacity ratio.
5. Confirm both figures and press ENTER. A successful result displays PASS.
6. If Err displays, open the error details, rectify the cause and repeat.

Do not return the system to service when

✕ Any switch or address setting remains unverified
✕ The detected indoor-unit count does not match the site
✕ The capacity ratio is incorrect or unexplained
✕ Addressing returns a failure or duplicate-address result
✕ An active or unexplained communication error remains

Technician completion checklist

☐ Before-and-after PCB photographs attached
☐ All connectors and earths secure
☐ All DIP and rotary switch settings verified
☐ Readdressing completed where required
☐ Detected indoor-unit count matches the site
☐ Capacity ratio confirmed and PASS displayed
☐ Heating and/or cooling test operation completed
☐ No active or unexplained fault remains
Where the SOP and model-specific manufacturer instructions differ, stop and contact GENERAL Technical Support.
For authorised service personnel only.