Aircon Not Cold After Servicing

Case Details

What We Checked

• Compressor running normally with no overheating or abnormal cycling — supply current measured at 5.2A, within the rated range for this Daikin model.
• Refrigerant pressure at the gauge port appeared normal on the high side, reading 18 bar on the discharge line.
• Outdoor service valve not fully reopened — sitting approximately a quarter-turn short of the fully open position, partially restricting flow through the circuit.
• Indoor coil barely cold to the touch despite the compressor running — surface temperature measured at 19°C versus the expected 8–12°C range for normal operation.
• Suction line pressure at the outdoor unit read lower than expected, consistent with a flow restriction upstream rather than a refrigerant shortage.

The Diagnosis

During the routine service, the outdoor service valve had been closed to isolate the refrigerant circuit for pressure checks. After the work was completed, the valve was turned back but not fully reopened — it sat about a quarter-turn short of the fully open position. That partial restriction throttled the refrigerant flow rate through the circuit. Enough liquid passed for the compressor to cycle without tripping on low pressure, but the reduced volume meant the indoor evaporator coil could not absorb enough heat from the room air. The compressor ran at normal current, the fan blew at full speed, and pressures looked acceptable on a quick gauge check — but the air coming out was warm because the coil was starved of refrigerant.

What Fixed It

We fully reopened the service valve and measured the temperature differential across the indoor coil — the drop returned to the normal 8–10°C range within minutes. Suction pressure climbed back to the expected reading for this Daikin model, confirming full refrigerant flow had been restored. We then checked all other valve positions and flare connections along the service path to confirm nothing else had been left loose or partially closed. We also ran the unit for twenty minutes while monitoring compressor current draw with a clamp meter to verify stable operation under load. No parts were needed, no refrigerant was lost, and the compressor required no further attention.

Cold air returned within minutes. The unit reached set temperature on the same visit, and no compressor work was required.

Why This Happens

Cooling loss right after servicing — service path first.

• Routine service involves opening valves and connections to access the refrigerant circuit. If any valve is left partially closed, refrigerant flow drops and cooling fails within hours or days. The failure is gradual because the restriction throttles flow rather than cutting it off — the system still circulates refrigerant, just not enough to absorb heat effectively.
• Timing is the strongest diagnostic clue. A unit that worked before a service and stopped working within two days almost certainly has a service-related cause. Always tell your technician the exact date of the last service visit so they can prioritise checking the service path before running broader diagnostics.
• A partially closed valve restricts flow without stopping it entirely. The compressor still runs and air still blows, but the air is warm. High-side pressure can read normal on a quick gauge check because the restriction is downstream — making it easy to misread as adequate refrigerant. This mimics a refrigerant leak or compressor fault, which is why the original contractor jumped to a compressor diagnosis.
• Ask your technician to check valve positions before running any pressure diagnostics. A quarter-turn on a service valve takes seconds to verify with a wrench and rules out the most common post-service failure. Comparing suction line temperature before and after full valve opening confirms the fix immediately.