Why Your AC Gas Top-Up Keeps Failing — Hidden Leak Inside Walls

Many homeowners and facility managers face a frustrating and costly air-conditioning problem: the aircon works fine immediately after a gas top-up, but within weeks—or sometimes days—the cooling performance drops again. The technician tops up the gas once more, the cooling returns briefly, and the cycle repeats.

If this sounds familiar, the issue is not the gas.The real problem is usually a hidden

refrigerant leak inside walls or concealed piping.

This blog explains why AC gas top-ups keep failing, how hidden leaks occur, the risks of ignoring them, and the correct long-term solution—especially relevant for Singapore homes, condos, offices, and commercial spaces where concealed piping is common.

Understanding How AC Gas Works

Air-conditioning systems rely on refrigerant gas (commonly called “AC gas”) to absorb heat from indoor air and release it outdoors. Importantly:

• Refrigerant is not consumed

• A properly installed system should never need repeated gas top-ups

• Gas only escapes when there is a leak

If gas levels keep dropping, the system is losing refrigerant continuously.

Why Gas Top-Up Is Only a Temporary Fix

A gas top-up treats the symptom, not the cause.

When technicians add refrigerant without repairing the leak:

• Cooling improves temporarily

• Gas continues leaking

• Performance drops again

• More money is spent on repeated top-ups

This is similar to refilling water in a leaking pipe without fixing the crack.

The Real Culprit: Hidden Leaks Inside Walls

What Is a Concealed Pipe Leak?

In many HDB flats, condominiums, and commercial buildings, AC refrigerant pipes are:

• Embedded inside walls

• Concealed above ceilings

• Covered behind tiles or plaster

Over time, these concealed pipes can develop leaks that are not visible.

Common Causes of Hidden Aircon Gas Leaks

1. Poor Installation Quality

Improper flaring, brazing, or joint tightening during installation can cause slow leaks that appear months or years later.

2. Copper Pipe Corrosion

Moisture, cement residue, or chemical reactions inside walls can corrode copper pipes, leading to pin-hole leaks.

3. Vibration and Building Movement

Natural building movement, vibrations from compressors, or renovations can stress concealed joints.

4. Aging Piping System

Older aircon systems (10+ years) often suffer from weakened pipe material and joint failures.

5. Renovation or Drilling Damage

Wall drilling for shelves, cabinets, or electrical works may accidentally damage concealed AC piping.

Signs You Have a Hidden Aircon Gas Leak

Look out for these warning signs:

• ❄️ Cooling improves briefly after gas top-up, then drops again

• 💸 Frequent gas top-ups within months

• ⚡ Higher electricity bills due to inefficient cooling

• 🧊 Ice forming on indoor unit piping

• 🌬️ Weak airflow despite clean filters

• 🛑 Outdoor unit cutting off frequently

If two or more signs appear together, a concealed leak is very likely.

Why Repeated Gas Top-Ups Are Dangerous

1. Compressor Damage

Low refrigerant levels cause the compressor to overheat. Compressor replacement is one of the most expensive aircon repairs.

2. Increased Energy Consumption

An under-gassed system works harder, consuming more electricity while delivering less cooling.

3. Environmental Impact

Refrigerant gas is harmful to the environment if released continuously.

4. Escalating Repair Costs

Ignoring leaks often leads to:

• Major pipe replacement

• Ceiling or wall hacking

• System downtime

Why Some Technicians Keep Doing Gas Top-Ups

Unfortunately, not all service providers perform proper diagnostics. Gas top-ups:

• Are quick and easy

• Cost less upfront

• Avoid difficult leak detection work

However, this approach benefits the short term only, not the customer.

A professional contractor should always recommend leak detection if gas loss repeats.

How Hidden Leaks Are Properly Detected

1. Pressure Testing (Nitrogen Test)

Nitrogen is pressurized through the piping system to check pressure drop—an accurate way to confirm leaks.

2. Soap Bubble Test

Applied to exposed joints to identify bubbling at leak points.

3. Electronic Leak Detection

Sensitive tools detect refrigerant traces around concealed areas.

4. Sectional Isolation Testing

Piping sections are isolated to pinpoint which part of the system is leaking.

The Correct Long-Term Solutions

Option 1: Repair Accessible Leak Points

If the leak is near exposed joints or indoor/outdoor units, targeted repair may be possible.

Option 2: Pipe Rerouting (No Hacking)

A common and effective solution in Singapore:

• Abandon leaking concealed pipes

• Install new exposed piping above ceiling or along walls

• Minimal disruption and faster completion

Option 3: Concealed Pipe Replacement (With Hacking)

Used when aesthetics require concealed piping:

• Wall or ceiling hacking required

• Higher cost and longer downtime

• Usually done during renovation

After repair or rerouting, the system is:

• Vacuumed

• Pressure tested

• Recharged with the correct refrigerant amount

Why “Just Top-Up” Is Never a Real Fix

If your AC keeps losing gas:

• The system is telling you something is wrong

• Repeated top-ups waste money

• Delayed action increases repair scope

A professional approach always focuses on root-cause rectification, not repeated refilling.

Preventing Future Aircon Gas Leaks

• Use licensed and experienced installers

• Avoid drilling walls without checking concealed services

• Perform annual professional servicing

• Address cooling issues early

• Avoid cheap, rushed installation work

When Should You Take Action?

You should stop gas top-ups and request proper inspection if:

• Gas is topped up more than once in a year

• Cooling lasts less than 3–6 months after refill

• Your system is older than 7–10 years

• Renovation work was recently done near AC piping

Final Thoughts

An air-conditioning system does not consume gas.If your AC gas top-up keeps failing, the problem is almost certainly a hidden refrigerant leak inside walls or ceilings.

Ignoring it leads to:

• Higher bills

• Poor comfort

• Major component failure

Fixing it properly restores:

• Stable cooling

• Energy efficiency

• Long-term reliability

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Need Professional Aircon Leak Detection & Rectification?

📞 Call / WhatsApp: +65 8151 8857🌐 Website: www.aotrinitysg.com.com

Alpha & Omega Trinity Pte LtdTrusted specialists in air-conditioning diagnostics, concealed pipe repairs, and long-term solutions—done right the first time.