Braemar VRF Outdoor Units – AO / A0 "ready for debugging" Debugging, Commissioning & Troubleshooting Guide (Installation & Startup Requirements)
Click below links to access Braemar VRF Service/ Installation/Owners Manuals and Technical Specifications
VRF REVERSE CYCLE SERVICE AND INSTALLATION: Seeley International Pty Ltd
This article is a guide only so please ensure all installation work is carried out in strict accordance with the instructions provided in the relevant manuals. Adhering to these guidelines is essential for safe operation, effective commissioning, and warranty compliance.
When Commissioning & Debugging Are Required
Commissioning and debugging are mandatory in the following situations:
1. New System Installation
- Installation of any new Braemar Mini VRF / MCMX / MCSX / MCSXB / MCHX / MCRX system.
- Adding new indoor units or branch boxes to an existing system.
- Changes to piping layout or refrigerant line configuration.
2. Component Replacement
- Outdoor PCB replacement (minimum 2 hours preheat).
- Compressor replacement.
- Branch selector replacement (MCRX 3‑pipe systems).
- Communication wiring repairs or rewiring.
3. Refrigerant System Work
- Full system recovery and recharge.
- Major leak repair.
- Addition or extension of refrigerant pipework.
4. Control or Addressing Changes
- Changing wall controller addressing.
- Switching between group control / shared control setups.
- Reconfiguring primary or secondary outdoor units.
Failure to re‑commission will cause issues such as:
Mode conflict, poor performance, addressing errors, U4 refrigerant lacking, C2 communication fault, or L4 over‑current.
Applicable Models
- Mini VRF
- MCMX Series
- MCSX Slim Series
- MCSXB
- MCHXB
- MCRX
- MCRXB
1. Preparation Before Commissioning
- Ensure all installation work is completed.
- Power must be ON for all indoor units and wall controllers. Wall controllers should display A0 (Ready for Debugging).
- Set wall control parameters correctly:
- Group Control: One wall controller controlling multiple indoor units. All units must share the same group address.
- Shared Control: Multiple wall controllers controlling one indoor unit. Each controller must have a unique address.
- Ensure address settings are correct to prevent mode conflicts.
- Compressor Preheat:
- Recommended 8 hours for all models.
- Minimum 2 hours after PCB replacement.
- Refrigerant must be pre-charged to at least 70% before debugging.
- Do not begin debugging unless A0 is displayed. Refer to the status chart if otherwise.
- Use Braemar controls for initial debugging before connecting third-party or central controllers.
- Install a 120Ω resistor across D1 and D2 terminals of the last indoor unit (or last branch box for MCRX systems).
2. Commissioning Sequence Overview
PCB Button Access
- 4-button PCB: Hold SW3 for 5 seconds.
- 8-button PCB: Hold SW7 for 5 seconds.
Debugging steps – for Outdoor units with 4 push buttons – SW3 for 5 seconds
Debugging steps – for Outdoor units with 8 push buttons – SW7 for 5 seconds
3. Refrigerant Charging Guidelines
- Refer to the specific installation manual for your model.
- Pre-charge with ≥70% refrigerant before debugging.
- Do not open service valves until refrigerant is added.
- Use electronic scales for accurate charging.
- Insulate refrigerant lines properly.
- Record refrigerant amounts for warranty and maintenance.
Click below links to access Braemar VRF Installation Manuals
VRF REVERSE CYCLE SERVICE AND INSTALLATION: Seeley International Pty Ltd
4. Common Troubleshooting Issues
Problem | Cause | Remedy |
Unit does not run | Power failure, fuse blown, low voltage | Check power supply and reset breaker |
Compressor runs continuously | Thermostat setting, dirty filters | Adjust settings, clean filters |
Insufficient cooling/heating | Gas leak, poor insulation | Repair leak, insulate lines |
Clicking sound | Normal expansion/contraction | No action needed |
Indoor unit not responding | Communication fault, address conflict | Check wiring, reassign addresses |
Rapid cycling | Incorrect refrigerant charge, sensor fault | Verify charge, inspect sensors |
5. Error Code Reference
Code | Description |
L4 | Over-current protection |
E1 | High-pressure sensor fault |
J9 | Low pressure ratio protection |
U4 | Refrigerant-lacking protection |
C2 | Communication fault (main ↔ compressor driver) |
F3 | Discharge temperature protection |
H6 | Indoor fan motor fault |
Refer to installation manuals for full error code tables.
6. Function Settings (Post-Debugging)
- Access via SW1 on master unit (for MCMX & MCSX)
- Access via SW3 on master unit (for MCHX (2 pipe)/MCRX (3-pipe) require advanced setup (e.g. DIP switch settings for primary/secondary outdoor units).
- Functions include:
- Silent Mode (Smart Night / Compulsory)
- Heating/Cooling Mode Lock
- Forced Defrosting
- Static Pressure Adjustment
- Outdoor unit sequence and capacity settings
7. Commissioning Checklist
- All Joints leak-tested and confirmed leak free
- Pipe insulation complete
- Drainage secure and flowing correctly
- Wiring connections tight and correctly terminated
- Correct addressing of all indoor units and controllers
- Communication wiring polarity consistent
- System operates in both cooling and heating
- Customer instructed on operation and maintenance requirements
- Full commissioning sheet completed and stored
8. Maintenance Schedule
Monthly
- Clean air filters
- Check for abnormal noise or vibration
Annually
- Refrigerant level inspection
- Indoor/outdoor coil cleaning
- Fan and motor check
- Electrical tightening
- Controller and sensor calibration
Years 1–5
- Documented annual service recommended for warranty support
Click below links to access Braemar VRF Service/ Installation/Owners Manuals and Technical Specifications
VRF REVERSE CYCLE SERVICE AND INSTALLATION: Seeley International Pty Ltd
This article is a guide only so please ensure all installation work is carried out in strict accordance with the instructions provided in the relevant manuals. Adhering to these guidelines is essential for safe operation, effective commissioning, and warranty compliance.