4 Jul 2024

Aircon Gas Leak Repair – Midea MS4OD-28 at 805C Keat Hong Close HDB on 2 Jul 2024

  • Project location

    805C Keat Hong Close HDB

  • Property type


Aircon gas leak repair -brazing process on the small leaking points at 805C Keat Hong Close HDB - 2 Jul 2024


Initially, we measured the gas pressure at 10 PSI and given the customer's report of the recent gas recharge three days prior, we suspected a gas leak. We employed a refrigerant leak detector to inspect the fins and coils of FCU 1, 2, and 3. Additionally, we inspected the fins and coil of the central unit (CU). Ultimately, the refrigerant leak detector identified the leak at the coil of the CU.


To braze and seal the leak point on the Media aircon CU's coil and charge 2.5 kg of R410A gas according to the manufacturer's specifications, we conducted a heat transfer analysis. Following the aircon gas leak service, the heat transfer delta was 11°C.

Aircon Gas Leak Repair for Midea MS4OD-28 Condenser Unit

Existing Condensing Unit (CU) Model:

Midea MS4OD-28


Existing Fan Coil Unit (FCU) Model:

Reason for the service:

  • Loss of Cooling Capacity- The reason for the service is that the air conditioner isn’t cooling properly after a gas top-up a few days ago.

Aircon gas leak repair Job Scopes:

  1. Preparation
  • Gather Equipment: Assemble all necessary tools and materials, including a refrigerant leak detector (electronic or ultraviolet (UV) dye and light), soap solution, manifold gauge set, repair tools (e.g., welding or brazing equipment), and replacement refrigerant.
  1. Initial Inspection
  • Visual Inspection: Begin with a thorough visual inspection of all accessible refrigerant lines, joints, and connections for signs of oil residue, corrosion, or physical damage, which can indicate potential leak points.
  1. Using a Refrigerant Leak Detector
  • Electronic Detector: An electronic leak detector is sensitive to the presence of refrigerant gases.
    Slowly move the probe along the refrigerant lines, paying close attention to joints and connections.
    The detector will alert you to the presence of refrigerant.
  1. Repairing Leaks
  • Small Leaks: For minor leaks at joints or connections, it may be possible to repair them by tightening or replacing fittings.
  • Welding or Brazing: For a small leak, brazing is sufficient to cover the hole.
    Larger leaks or those in the piping may require cutting out the damaged section and welding or brazing a new piece of pipe.
    First, clean around the gas leak area using sandpaper to clearly identify the leaking points on the condensing coil.
    Cleaning not only improves visibility but also removes oxidation, paint, and debris.
    Ensure the area is clean and free from any refrigerant or oils before welding.
  • Replace Components: In some cases, it may be necessary to replace the entire section of piping or faulty components.
    Additional charge applies.
  1. Post-Repair Testing
  • Vacuum the System: Once repairs are completed, use a vacuum pump to evacuate the system. This removes air and moisture.
  • Checking for leaks: Hold the Vacuum: After the vacuum process is complete, turn off the vacuum pump and observe the pressure reading on the gauge for a few minutes.
    If the pressure remains stable, the system is likely free of leaks.
    If the pressure increases, it indicates a leak that must be located and repaired before proceeding.
  1. Recharge Refrigerant
  • Calculating Refrigerant Quantity: Determine the factory-specified refrigerant charge for the system, typically noted on the data plate of the outdoor unit.
    Adjust the length of the piping as necessary, using guidelines found in the manufacturer’s installation manual.
  • Refrigerant Cylinder Preparation: Place the refrigerant cylinder on the scales and connect the yellow hose to the cylinder.
    Open the cylinder valve slightly to purge air from the hose, then close the valve.
  • Initiating Charging: Open the low side valve on the manifold gauge to allow the refrigerant to flow into the system.
    Monitor the scales to ensure the correct amount of refrigerant is added.
  • Finishing the Charge: Once the specified weight of refrigerant has been charged, close the manifold gauge valves, and disconnect the hoses.
  1. Final Checks and Start-up
  • Re-check for Leaks: Perform a final leak check to ensure system integrity.
  • Start-up the System: Restore power to the air conditioning unit and start it. Observe the operation for a few minutes to ensure it is functioning correctly.
  • Performance Check: Measure the temperature drop across the indoor unit to assess cooling performance, including suction line temperature and pressure, FCU return air and off-coil air temperatures, and superheat value.
  1. Documentation and Cleanup
  • Record Keeping: Document the process, including the amount of refrigerant charged, and any repairs carried out.
  • Clean-up: Ensure all caps are replaced on service valves, tools are collected, and the work area is clean.


Our Aircon Services

  1. System Analysis
  2. Refrigerant renewal
  3. Refrigerant pipe leak repair
  4. Condenser Unit Alkaline Wash
  5. Alkaline Wash with FCU Component Removal
  6. Alkaline Wash without FCU Component Removal
  7. FCU Essential Servicing


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