Cassette not cooling: stuck gas-flow valve, not compressor
The cassette unit pushed air but the air stayed warm. A previous contractor pointed to the compressor and quoted a full replacement. We checked gas flow before agreeing, and the fault sat upstream at the expansion valve, the part that meters gas into the indoor coil.
By Team Snowflake | Reviewed 10 Mar 2026
Case summary
Daikin Cassette9 years oldIndustrialPioneer, Singapore
- Concern
- The previous quote was for a full compressor replacement. That is several times the cost of the actual fix.
- Found
- Gas-flow valve stuck partly closed, restricting cooling to the indoor coil
- Key check
- Checked whether gas was reaching the indoor coil before blaming the compressor
- Result
- Full cooling came back after the valve replacement. The compressor was confirmed healthy and kept in place. The repair cost a fraction of the compressor replacement quote, and the owner avoided paying for a part that was never the problem.
What we were told
The aircon in the factory office stopped cooling about a week ago. The fan still runs, but the air coming out is warm. A contractor had already looked at it and said the compressor was losing capacity and needed replacing. The owner wanted a second opinion before approving that cost.
What we checked
We first checked whether the compressor was moving gas at all, then whether enough gas was actually reaching the indoor coil. That order matters. A healthy compressor can still blow warm air if a small flow-control part downstream is stuck. Blaming the compressor first risks replacing an expensive part that works, while the cheap part that failed goes untouched.
The compressor was running normally and moving gas, which did not match the failing-compressor story.
Gas flow into the indoor coil was restricted, so the coil was being starved despite a working compressor.
The gas-flow valve, the part that meters gas into the coil, was stuck partly closed.
The control board was still sending the open command, so the valve was the fault, not the electronics telling it what to do.
What we found
The gas-flow valve had seized in a partly closed position. Only a small amount of gas could pass through, so the indoor coil never got enough to absorb heat from the room. The compressor itself was healthy. The whole problem was the one stuck valve sitting between it and the coil.
What fixed it
We explained that the compressor was healthy and did not need replacing. The fix was much smaller: swap out the stuck gas-flow valve, recharge the gas, and test the system end to end. Once the new valve was fitted, gas flowed freely to the coil and the indoor unit cooled within minutes.
Outcome
Full cooling came back after the valve replacement. The compressor was confirmed healthy and kept in place. The repair cost a fraction of the compressor replacement quote, and the owner avoided paying for a part that was never the problem.
What this case teaches us
Warm air does not always mean a failed compressor
- A running compressor can still leave a room warm if a stuck valve blocks gas from reaching the indoor coil. The fan and the noise can sound completely normal.
- The expansion valve meters how much gas flows into the coil. When it seizes partly closed, the coil starves and cannot pull heat from the room, even though the compressor is fine.
- Before approving a compressor replacement, ask whether gas flow to the indoor coil was tested. That one check separates a small valve repair from a major rebuild.
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