Braemar VRF / MCMX – Commissioning & Re‑Commissioning Checklist

Post Installation, PCB Replacement & System Configuration Changes

⚠️ Safety Notice – Reverse Cycle Air Conditioners

This equipment must only be installed, commissioned, serviced and repaired by suitably qualified and licensed personnel.

Before commencing work, complete a task-specific risk assessment and ensure electrical isolation procedures, safe access, adequate service clearances and appropriate PPE have been considered. All work must comply with applicable regulations, standards and manufacturer requirements.

Particular care must be taken when working around electrical systems, refrigerant circuits, moving parts, roof spaces, ceiling spaces, confined spaces and working-at-heights hazards where applicable.

Do not proceed if safe access, required clearances, confined space risks or appropriate safety controls cannot be achieved and maintained. 

Safety takes priority over diagnosis, repairs, installation schedules and customer expectations. If the task cannot be completed safely, it must not proceed until the risks have been adequately controlled.

This article defines the mandatory commissioning and re‑commissioning process for:

• Braemar VRF MCMX systems
• New system installations
• System expansions or reconfiguration
• Replacement of:
  • Outdoor unit main PCB
  • Compressor drive board
  • Fan drive board
  • Indoor unit PCBs

Why This Checklist Is Critical

Failure to complete commissioning correctly will guarantee repeat faults, most commonly:

• C5 – IDU Project Code Conflict
• C6 – ODU Quantity Inconsistency
• CC / CF / CJ – Master & addressing errors
• U0 – Insufficient compressor preheating
• U2 – Capacity code / DIP switch error
• U4 – Lack of refrigerant protection

Commissioning is NOT optional after PCB replacement or any system layout change.

Primary Reference Manuals (With Page Numbers)

When Commissioning MUST Be Performed

Commissioning or re‑commissioning is mandatory when:

• New VRF system installation is completed
• Outdoor unit main PCB is replaced
• Compressor or fan drive PCB is replaced
• Indoor unit PCB is replaced
• Indoor units are added or removed
• Outdoor units are added or removed
• Communication wiring is modified
• DIP switch settings are changed

MCMX‑03‑B – Commissioning overview, pp. 10–13

Pre‑Commissioning Checklist (Before Power‑On)

1. Electrical & Wiring Verification

Confirm before energising the system:

• Correct mains voltage present at ODU
• Voltage within allowable limits under load
• All indoor & outdoor units powered
• Verified earth continuity
• Communication wiring (D1 / D2) daisy‑chained correctly
• Shield earth connected at ODU only
• Matched resistor installed at final indoor unit

MCMX‑03‑B – Electrical Part: pp. 14–17

2. Refrigerant & Piping Checks

• Pipework pressure‑tested
• System evacuated fully
• Refrigerant charge added per total pipe length
• Gas and liquid service valves fully open
• No refrigerant leaks detected

MCMX‑03‑B – Refrigeration & charging references, pp. 8–9 & 10–11

3. DIP Switch & Hardware Configuration

• One (and only one) Master Outdoor Unit selected (SA8)
• All other ODUs set as slave
• Capacity DIP switches correctly set for model
• Emergency operation DIP switches disabled

VRF Flowcharts Manual:

• Master/DIP logic – Section C, pp. 17–19
• Capacity/DIP validation – Section U, p. 63

Mandatory Compressor Pre‑Heating

Critical Requirement – Do NOT Skip

• ODU must be powered continuously for a minimum of 8 hours
• Allows compressor crankcase heater to stabilise oil temperature

Failure results in:

• U0 – Insufficient Compressor Preheat
• High risk of compressor damage

MCMX‑03‑B – Debugging & preheat confirmation: pp. 12–13

Commissioning Procedure (Outdoor Unit Debug Mode)

MCMX‑03‑B – Test Operation & Debugging: pp. 10–13

Step 1 – Enter Debug / Commissioning Mode

• Access outdoor unit PCB
• Press & hold SW7 (Commissioning Button) as specified
• Confirm system enters debug sequence

Step 2 – Address Allocation

• System automatically allocates:
  • ODU addresses
  • IDU addresses
• Confirm indoor unit count matches installed units

Incorrect count will later trigger:

• C4
• C5
• C6

Step 3 – Outdoor Unit Quantity Confirmation

• System confirms number of connected ODUs
• Any mismatch triggers C6

Correct wiring or power issues before proceeding

Step 4 – Indoor Unit Quantity Confirmation

• Confirm detected IDU quantity
• Manually correct if prompted

Common faults if skipped:

• C4 – IDU Missing
• C5 – Project Code Conflict

Step 5 – Capacity Ratio Validation

System checks IDU vs ODU capacity:

VRF Flowcharts Manual – Capacity logic: pp. 18–20

Step 6 – Outdoor Component Self‑Check

System evaluates:

• Compressor
• Outdoor fans
• Sensors
• Drive boards

Any detected fault must be cleared before proceeding.

Step 7 – Indoor Component Self‑Check

System checks:

• Indoor fan operation
• Sensors
• Drain components

VRF Flowcharts Manual – Indoor checks: pp. 47–50

Step 8 – Refrigerant & Valve Confirmation

System verifies:

• Refrigerant pressure relationship
• Valve position

Faults here include:

• U4 – Lack of Refrigerant
• U6 – Valve abnormality

VRF Flowcharts Manual – Section U: pp. 63–64

Step 9 – Commissioning Operation Run

• System runs in:
  • Cooling or
  • Heating (ambient dependent)
• Monitor minimum 20 minutes stable operation

Step 10 – Commissioning Complete

• System exits debug mode
• Returns to standby
• No active fault codes present

Commissioning successful

Re‑Commissioning After PCB Replacement

When any PCB is replaced, stored commissioning data is lost.

Always perform:

• Full commissioning cycle
• Do not skip steps
• Do not attempt partial commissioning

Skipping recommissioning most commonly leads to:

• C5 / C6
• CC / CF
• U0 / U2 / U4

MCMX‑03‑B – PCB replacement & recommissioning notes: pp. 10–13

Final Verification (Before Leaving Site)

Confirm:

• No active fault codes
• Indoor units respond correctly
• System heats/cools as expected
• Correct indoor unit grouping
• Stable operation for ≥20 minutes

Key Technician Takeaways

• Commissioning is a system‑defining process
• Any skipped step can cause system‑wide faults
• PCB replacement always requires recommissioning
• Proper commissioning prevents repeat visits and ongoing issues