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HVAC 853 HVAC REFRIGERATING CYCLE TROUBLE- SHOOTING 1. INSUFFICIENTREFRIGERANT Condition • Air conditioner does not cool effectively Symptoms in refrigerant cycle • Pressure on both the high and low pressure sides is low • Air around the air outlet is slightly cold Cause • There is gas leakage in the refrigerating cycle Diagnosis • Insufficient refrigerant in the refrigerating cycle • Refrigerant leakage Countermeasures • Locate the leaking and repair • Recharge refrigerant to the specified amount 2. EXCESSIVE REFRIGERANT OR INSUFFICIENT CONDENSER COOLING Condition • Air conditioner does not cool effectively Symptoms in refrigerant cycle • Pressure on both the high and low pressure sides is high. Cause • Refrigerant is overcharge in the refrigerating cycle, causing poor cooling performance. • Condenser cooling performance is poor • Fluid coupling on fan is slipping Diagnosis • Excessive refrigerant in the refrigerating cycle • Overcharged refrigerant • Poor condenser cooling performance • Condenser fins blocked or fan belt loose • Slipping radiator fan fluid coupling • Silicone oil leaking from the coupling Countermeasures • Clean the condenser • Tighten the AC belt to the correct tension 3. ENTRY OF MOISTURE IN THE REFRIGERANT CYCLE Condition • Air conditioner alternately cools and does not cool Symptoms in refrigerant cycle • During operation, the pressure on the low pressure side alternates between vacuumand normal Cause • The moisture mixed in the refrigerant in the refrigerating cycle freezes in the expansion valve orifice, blocking the cycle. After a time, the ice melts and normal conditions return Diagnosis • The drier is in an oversaturated condition • The moisture in the refrigerating cycle freezes the expansion valve orifice, impeding refrigerant circulation Countermeasures • Remove the moisture by repeated evacuation • Recharge new refrigerant to the specified amount 4. REFRIGERANT FAILSTOCIRCULATE Condition • Air conditioner does not cool Symptoms in refrigerant cycle • Pressure on the low pressure side is vacuum and pressure on the high pressure side is extremely low • Frost or dew is formed on the piping at the front and rear side of the receiver or the expansion valve Cause • Moisture or dirt in the refrigerating cycle freezes or sticks to the expansion valve orifice, obstructing refrigerant flow. • Gas leaking from the heat sensitizing tube of the expansion valve obstructs refrigerant flow Diagnosis • Blocked expansion valve orifice Countermeasures • Allow to stand for some time and then resume operation to decide whether the blockage is caused bymoisture or by dirt. If caused bymoisture; remove