How can a gas leak be mistaken for compressor failure?

When refrigerant is too low, the compressor shuts down to protect itself. A technician who does not check the gas level first may see the compressor not running and conclude it has failed.

How do you confirm the compressor is actually fine?

By sealing any leaks, recharging the system to the correct level, and then testing the compressor. If it starts and runs with normal current draw and pressure, it is functional.

Should I always get a second opinion before replacing a compressor?

If the system is less than seven years old and there are no obvious signs like unusual noises or electrical damage, a second opinion is a good idea. Gas leaks are more common than compressor failures at this age.

LG Gas Leak Misdiagnosed As Compressor Failure

Aircon case in Bedok, Singapore: cooling loss traced to refrigerant leak at corroded outdoor unit connections — compressor was functional after targeted diagnosis checks.

Case Details

Reported: My previous contractor said the compressor is gone and I need a new one. The quote was over $2,000. The system is only five years old so I was surprised. I want to get a second opinion before I pay that much.
Unit: LG · Wall-mounted · 5 years old
Location: HDB · Bedok, Singapore

What We Checked

Refrigerant pressure was critically low — well below the range needed for the compressor to operate.
Outdoor unit pipe connections showed corrosion and green oxidation.
Bubble test confirmed an active leak at the gas line connection on the outdoor unit.
Indoor unit flare joints showed no signs of leakage.
LG error code CH35 was active, indicating low-pressure protection — the compressor was shutting down to protect itself, not because it had failed.

The Diagnosis

The compressor was not faulty. It had shut down because refrigerant pressure was too low for safe operation — a built-in safety mechanism. The actual cause was a gas leak at the corroded outdoor unit pipe connections. The previous contractor appears to have tested the compressor while the system was low on gas, found it would not start, and concluded it had failed. A compressor cannot run without adequate refrigerant. Once the leak was sealed and the system recharged, the compressor started and operated normally.

What Fixed It

We explained that the compressor was protecting itself from running without sufficient refrigerant. The fix was to seal the gas leak at the outdoor connections, recharge the system, and test the compressor under normal operating conditions. We welded the corroded connection, recharged the refrigerant, and confirmed the compressor ran with normal current draw and pressure readings. No compressor replacement was needed. We recommended monitoring the welded area for any future corrosion given the pipe condition.

The leak was welded and the system recharged. The compressor started immediately and ran normally. Cooling returned to full capacity. The homeowner saved over $2,000 by avoiding an unnecessary compressor replacement.

Why This Happens

Why gas leaks get misdiagnosed as compressor failure.

When refrigerant is too low, the compressor cannot build pressure. This can look like compressor failure to a technician who does not check for leaks first.
A compressor that will not start due to low gas is protecting itself — it is not broken.
Proper diagnosis requires checking for leaks before concluding the compressor has failed.
If the compressor runs normally once refrigerant is restored, the original diagnosis was wrong.

Same situation with your aircon?

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