My AC no longer cools: diagnosis before recharging

❄️ IDENTIFYING FAILURE SYMPTOMS

An air conditioning system that no longer cools generally shows several warning signs that should be carefully observed. The air blown may be lukewarm or even hot, despite being set to the minimum temperature. Airflow can also decrease noticeably, making the atmosphere stifling even after several hours of operation.

Abnormal noises are also valuable indicators. A struggling compressor, unusual hissing sounds or repeated banging can reveal a malfunction in the refrigerant circuit. Observing frost formation on the pipes or, conversely, a complete absence of condensation, provides additional clues about the state of the system.

Power consumption is another parameter to monitor. A failing system may consume more energy for a poor result, or conversely, show abnormally low consumption if certain components are no longer functioning correctly. This preliminary analysis directs the diagnosis toward the areas most likely to be affected.

🔍 VISUAL INSPECTION OF THE REFRIGERANT CIRCUIT

A visual examination of the refrigerant circuit is the first step in a rigorous diagnosis. Visible pipes, fittings and seals must be inspected carefully to detect any traces of oil or leaks. These greasy marks, often accompanied by dust, generally indicate an escape of refrigerant that compromises the efficiency of the system.

The condition of the filter driers deserves particular attention. These elements, essential for the proper functioning of the circuit, can become saturated and cause significant restrictions. A clogged filter creates abnormal temperature differences between the inlet and outlet, perceptible to the touch on accessible pipes.

Condensers and evaporators also require a thorough check. The accumulation of dust, leaves or debris on the fins considerably reduces heat exchange. A careful cleaning can sometimes restore a large part of the performance, without requiring more complex intervention. This preliminary check avoids confusing a maintenance issue with a major technical failure.

⚡ CHECKING ELECTRICAL COMPONENTS

The electrical system plays a crucial role in the optimal operation of an air conditioning installation. The compressor, the true heart of the refrigerant circuit, must be tested first. A multimeter allows you to check winding continuity and detect any short circuits or breaks. The resistance values must match the manufacturer's specifications to ensure optimal operation.

The fans of the outdoor and indoor units also require a thorough check. Their proper functioning directly conditions the efficiency of heat exchange. A faulty fan can cause the compressor to overheat and compromise the entire system. Checking electrical connections, which are often victims of humidity and corrosion, frequently reveals contact problems.

Temperature and pressure sensors directly influence system regulation. A defective sensor can distort the information transmitted to the control system, causing unexpected shutdowns or operation in degraded mode. Checking these elements, often overlooked, can identify malfunctions that only require a simple replacement rather than major work on the refrigerant circuit.

📊 PRESSURE AND TEMPERATURE MEASUREMENTS

Pressure analysis is one of the most revealing diagnostics for assessing the condition of a refrigerant circuit. Gauges connected to the high and low pressure ports provide crucial information about the refrigerant charge level. Abnormally low pressures on both sides generally indicate a significant leak, while normal high pressure with too low a low pressure suggests a restriction in the circuit.

Temperatures measured at different points in the circuit effectively complement the pressure analysis. The superheat temperature at the compressor inlet and the subcooling temperature at the condenser outlet provide precise information about the quantity of refrigerant present in the system. These values, compared with manufacturer data, allow you to determine whether a recharge is necessary or whether other problems are at play.

Using an infrared thermometer greatly facilitates these measurements without requiring disassembly. Abnormal temperature differences between different sections of the circuit often reveal partial obstructions or component failures. This non-invasive approach allows precise targeting of subsequent interventions and avoids unnecessary disassembly. A complete thermal diagnosis can also detect insulation problems or thermal bridges that affect the overall efficiency of the system.

🛠️ TESTING WITH SPECIALISED TOOLS

Using professional refrigeration tools transforms an approximate diagnosis into a precise and reliable analysis. The electronic leak detector allows you to pinpoint refrigerant escapes with precision, even the smallest ones that escape visual inspection. These devices, with remarkable sensitivity, detect concentrations of just a few parts per million and direct you straight to the area to be repaired.

The vacuum pump is an indispensable tool for assessing circuit tightness after repair. A prolonged vacuum test reveals the presence of any micro-leaks that would quickly compromise a new refrigerant charge. This step, often skipped out of haste, nevertheless determines the lifespan and effectiveness of the repair.

The refrigerant analyser adds an additional dimension to the diagnosis by precisely identifying the composition of the refrigerant present in the circuit. This analysis detects any mixtures, contaminations or degradations that require a complete evacuation before recharging. The use of modern ecological refrigerants makes this verification essential to guarantee optimal performance and comply with the environmental standards in force in 2026.

🔧 ACTION PLAN BEFORE RECHARGING

Once the complete diagnosis has been carried out, establishing a structured action plan avoids disorganised interventions and premature recharges. The first priority is always to repair all identified leaks, even the most minor ones. A recharge performed on a non-airtight circuit represents a waste of costly refrigerant and avoidable environmental pollution.

Replacing faulty components must precede any circuit recharge. Saturated filter driers, defective expansion valves or failing sensors compromise system efficiency and can damage other elements. This preventive approach, although involving a higher initial investment, guarantees a lasting repair and avoids repeated interventions.

The final verification of tightness by nitrogen pressure test validates the effectiveness of repairs before the actual recharging phase. This crucial step, carried out at a pressure higher than normal operating pressure, guarantees the absence of new leaks. Following this procedure ensures an effective and long-lasting recharge, fully justifying the investment in refrigerant and intervention time.

❄️ Air Conditioning Diagnosis Calculator

Identify the probable cause of your fault based on the observed symptoms