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A/C SYSTEMS DIAGNOSIS

A/C SYSTEMS DIAGNOSIS. DIAGNOSIS TROUGH PRESSURE READING. A/C TEST CONDITIONS Connect LP and HP line to gauges manifold Start the engine and let the cooling water reach 60 °C Switch on the A/C system Set engine speed to 2000 - 2500 Rpm Set blower to middle speed

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A/C SYSTEMS DIAGNOSIS

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  1. A/C SYSTEMS DIAGNOSIS

  2. DIAGNOSIS TROUGH PRESSURE READING A/C TEST CONDITIONS • Connect LP and HP line to gauges manifold • Start the engine and let the cooling water reach 60 °C • Switch on the A/C system • Set engine speed to 2000 - 2500 Rpm • Set blower to middle speed • Set heating system to full cold • Check ambient temperature value • Check LP and HP pressure reading • Compare the values with Working Pressure Table

  3. INSUFFICIENT COOLINGMalfunctions List LOW Pressure too high HIGH Pressure normal / too low • Possible causes: • Compressor clutch does not engage properly or sleeping • Expansion valve does not regulate, always open – (V) LP has small and fast oscillations • (V) Defective Stroke regulation control valve • Defective compressor

  4. INSUFFICIENT COOLINGMalfunctions List LOW Pressure too low HIGH Pressure normal / too high • Possible causes: • Expansion valve does not regulate, always closed, clogged • Low q.ty of refrigerant ( - 30%) • Receiver dryer blocked and or wet • Restriction on liquid line • (F) Defective thermostat • (V) Defective Stroke regulation control valve: max displacement

  5. INSUFFICIENT COOLINGMalfunctions List HIGH Pressure normal LOW Pressure normal • Possible causes: • Hot air leakages inlet after evaporator • Hot water leakages into heater core • Ice on evaporator core

  6. INSUFFICIENT COOLINGMalfunctions List HIGH Pressure too high LOW Pressure normal / too high • Possible causes: • Normal reading with high external temperature ( t > 43 °C ) • Refrigerant overcharge( + 35% ) • Condenser fins may be blocked or have not enough air flow • Air in A/C system • Obstruction on the HP line before the gauge connection.

  7. INSUFFICIENT COOLINGMalfunctions List” LOW Pressure normal / too low HIGH Pressure too low • Possibile causes: • Normal reading with external temperature quite low ( t < 5 °C ) • Low Refrigerant level (- 75% ) • Expansion valve blocked in closed position or clogged • Obstruction on LP line

  8. INSUFFICIENT COOLINGMalfunctions List Low and High pressures at the same level • Possible causes: • Compressor clutch does not engage properly or sleeping • Defective Stroke regulation control valve on compressor • Defective compressor • (V) Defective Stroke regulation control valve

  9. Thanks for your attention

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