Why do LG outdoor units tend to leak at the connections?

The connection layout on some LG and MHI outdoor units allows moisture to collect around the pipe joints. Over time, this causes corrosion that weakens the seal. It is not a defect — it is a wear pattern common with prolonged outdoor exposure.

Is welding a permanent fix for corroded connections?

It can seal the current leak, but if the surrounding pipe surface is also corroded, new weak points may develop nearby. We have seen cases where welding fixed one spot and another appeared within months.

Can I replace just the outdoor unit without changing the indoor units?

Yes, as long as the replacement outdoor unit is compatible with the existing indoor units. This is often the most practical middle-ground option when the indoor units are still in good condition.

LG Outdoor Unit Gas Leak at Pipe Connections

Aircon case in Bukit Batok, Singapore: cooling loss traced to refrigerant leak at corroded outdoor unit pipe connections after targeted diagnosis checks.

Case Details

Reported: The aircon has been topped up twice in the last few months. Each time cooling comes back for a few weeks, then drops again. My previous contractor said the gas keeps running low but didn't explain why.
Unit: LG · Wall-mounted · 9 years old
Location: HDB · Bukit Batok, Singapore

What We Checked

Refrigerant pressure was well below normal operating range.
Indoor flare joints showed no signs of leakage.
Outdoor unit pipe connections had visible corrosion and green oxidation around both joints.
Bubble test confirmed active bubbling at the corroded connection points on the outdoor unit.
Condenser coil was heavily clogged with dust and debris, consistent with the unit's age and outdoor exposure.

The Diagnosis

The pipe connections at the LG outdoor unit had corroded over the years. Moisture and weather exposure weakened the joint seals, creating small gaps where refrigerant escaped. This is a known pattern with older LG and some MHI outdoor units — the connection layout tends to trap water around the joints.

What Fixed It

We presented three options with honest trade-offs. First: weld the leaking joints and recharge. This is the lowest cost, but corrosion has spread along the pipe surface and new leak points may appear nearby — we have seen this happen. Second: replace the outdoor unit with a compatible LG unit. This addresses the corroded connections fully and resets the outdoor unit lifespan, though the indoor units stay. Third: replace the entire system. If the indoor units are also showing age-related wear, a full replacement avoids piecemeal fixes. The homeowner chose a full system replacement after considering the unit's age and the risk of chasing further faults across aging components.

The full system was replaced — new indoor and outdoor units installed, piping pressure-tested, and refrigerant charged to specification. Cooling has been stable since with no further gas loss.

Why This Happens

Why outdoor unit connections corrode on certain brands.

LG and some MHI outdoor units use connection layouts that trap moisture around pipe joints, accelerating corrosion over time.
Corrosion weakens the seal gradually — cooling loss appears slowly, not suddenly.
Welding can seal the current leak, but nearby corroded areas may develop new leaks later.

Same situation with your aircon?

Describe what’s happening. We’ll work out the likely cause and tell you the right next step.

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