SERVICE MANUAL
  Applies to: Hyundai Coupe/Tiburon 1998-2001
GROUP
Heating, Ventilation & Air Conditioning Air Conditioning System
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PERFORMANCE TEST DIAGNOSIS 

The test gauge indicators shown in the following chapter are to be used as typical examples of common problems which you may need to diagnose.

GAUGE READINGS
OTHER SYMPTOMS
DIAGNOSIS
CORRECTION
  • Discharge air: slightly cool.
  • Thermostatic switch (with thermistor): Low side gauge doesn't fluctuate with switch "ON" and "OFF" cycle.
Some air and moisture in system.
  1. Leak test system.
  2. Discharge refrigerant from system.
  3. Repair leaks as located.
  4. Replace receiver/drier (The drier is probably saturated with moisture.)
  5. Evacuate the system for at least 30 minutes.
  6. Charge system with refrigerant.
  7. Operate system and check performance.
  • Discharge air: Becomes warm as low side cycles into vacuum.
  • Discharge air: Becomes warm all the time during hot part of day.
Excessive moisture in system
  1. Discharge refrigerant.
  2. Replace receiver-drier.
  3. Evacuate system with a vacuum pump.
  4. Recharge system to proper capacity.
  5. Operate system and check performance.
  • Compressor: Cycles on and off too fast.
  • Low side gauge: Not enough range shown on low side gauge.
Defective thermo-
static switch
  1. Stop engine and turn air conditioning "OFF".
  2. Replace thermostatic switch when installing new thermostatic switch. Make sure that thermister tube is installed in the same position and to the same depth in evaporator core as old switch tube.
  3. Operate system and check performance.
GAUGE READINGS
OTHER SYMPTOMS
DIAGNOSIS
CORRECTION
  • Compressor: low side pressure builds too high before compressor turns on (cycle "ON" point too high)
Faulty thermo-
static switch
  1. Stop engine and turn air conditioning "OFF".
  2. Repair or replace thermostatic switch with thermistor (make sure that all wiring is positioned so that no short circuiting can occurred.)
  3. Operate system and check performance.
  • Discharge air: Slightly cool.
System slightly low on refri-
gerant
  1. Check leaks.
  2. Discharge refrigerant.
  3. Repair leaks.
  4. Check compressor oil level.
  5. Evacuate system using a vacuum pump.
  6. Charge system with refrigerant.
  7. Operate system and check performance.
  • Discharge air: Warm
  • System very low on refri-
    gerant
  • Poss-
    ible leak in system.
  1. Check leaks.
  2. Leak test compressor seal area very carefully.
  3. Discharge refrigerant.
  4. Check compressor oil level.
  5. Evaporate system using a vacuum pump.
  6. Charge system with refrigerant.
  7. Operate system and check performance.
  • Discharge air: Slightly cool.
  • Expansion valve: Sweating or frost build up.
  • Expansion valve stuck closed.
  • Screen plugged
  • Sensing bulb malfunction.
  1. Discharge system.
  2. Disconnect inlet line at expansion valve and remove and inspect screen.
  3. Clean and replace screen and reconnect inlet line.
  4. Evacuate system using a vacuum pump.
  5. Charge system with refrigerant.
GAUGE READINGS
OTHER SYMPTOMS
DIAGNOSIS
CORRECTION
  • Discharge air: slightly cool.
  • High side pipe: Cool and also shows sweating or frost.
Restric-
tion in high side of system
  1. Discharge system.
  2. Remove and replace receiver-
    drier, liquid pipes or other defective components.
  3. Evacuate system using a vacuum pump.
  4. Charge system with refrigerant.
  5. Operate system and check performance.
  • Compressor: Noisy

Compres-
sor malfunc-
tion
  1. Isolate compressor.
  2. Remove compressor cylinder head and inspect compressor.
  3. Check compressor oil level.
  4. Replace receiver-drier
  5. Operate system and check performance.
  • Discharge air: Warm.
  • High side pipe: Very hot

Malfunc-
tioning condenser over-
charge.
  1. Check for loose or worn fan belt.
  2. Inspect condenser for clogged air passage.
  3. Inspect condenser mounting for proper radiator clearance.
  4. Check for refrigerant overcharge.
  5. Operate system and check performance.
  • Discharge air: Slightly cool.
Large amount of air and moisture
  1. Discharge refrigerant from system.
  2. Replace receiver-drier which may be saturated with moisture.
  3. Evacuate system using vacuum pump.
  4. Charge system with refrigerant.
  5. Operate system and check performance.
  • Discharge air: Warm
  • Evaporator: Sweating or frost.
Expansion valve stuck open.
  1. Discharge system.
  2. Replace expansion valve, making sure all contacts are clean and secure.
  3. Evacuate system using vacuum pump, then recharge system with refrigerant.
  4. Operate system and check performance.