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A/c System General Diagnostic Procedures Hyundai Elantra I

General Servicing - All Makes 3 illustrations ~401 words

DESCRIPTION

Diagnosis is an important first step in A/C system servicing. To save time and effort, systems should be carefully checked to identify the causes of poor performance. By using the following diagnostic charts, defective components or system problems can be quickly located. To identify problems that are specific to one system, refer to the repair section of this manual. The charts in this section apply to all systems.

PREPARATION FOR TESTING

  1. Attach Low and High pressure gauges.
  2. Start engine and allow to warm up.
  3. Set system to COOL and blower to HIGH.
  4. Open car doors and hood.
  5. Run engine at fast idle for 2-3 minutes.

Air Conditioning System Performance Check. Scheme 24

Scheme 24: Air Conditioning System Performance Check
Scheme 24: Air Conditioning System Performance Check

Ambient Temperature/Pressure. Scheme 25

Scheme 25: Ambient Temperature/Pressure
Scheme 25: Ambient Temperature/Pressure

Evaporator Temperature/Pressure. Scheme 26

Scheme 26: Evaporator Temperature/Pressure
Scheme 26: Evaporator Temperature/Pressure

A/C DIAGNOSIS W/GAUGES FOR SYS. W/INSUFFICIENT OR NO COOLING

Low Side GaugeHigh Side GaugeOther Symptoms (1)Diagnosis
NORMALNORMALNo or few bubbles in sight glass. High side gauge may go high. Low side gauge does not fluctuate with compressor on/off cycle.Some Air & Moisturein System
NORMALNORMALCools okay in morning but not during hot part of day. Bubbles in sight glass. Discharge air warm when low side gauge drops into vacuum.Excessive Moisture in System
NORMALNORMALThermostatic sw. sys. only- compressor cycles off & on too rapidly.Defective Thermostatic Sw.
NORMAL to HIGHNORMALCycling clutch sys only - compressor doesn't turn on soon enough. Discharge air becomes warm as low side pressure rises.Misadjusted Thermostatic Sw. orDefective Pressure Sensing Switch
LOWLOWBubbles in sight glass. Outlet air slightly cool.Low R-12 Charge
LOWLOWSight glass clear. Outlet air very warm.Excessively Low R-12 Charge
LOWLOWOutlet air slightly cool. Sweating or frost at expansion valve.Expansion Valve Stuck Closed Screen Plugged or Sensing Bulb Malfunction
LOWLOWOutlet air slightly cool. High side line cool to touch. Sweating or frost on high side.Restriction on High Side
LOWHIGHEvaporator outlet pipe cold. Low side goes into vacuum when blower is disconnected.STV Stuck Open
HIGHLOWEvaporator outlet pipe warm. Outlet air warm.STV Stuck Closed
HIGHLOWNoise from compressor.Compressor Malfunction
HIGHHIGHOutlet air warm. Liquid line very hot. Bubbles in sight glass.Compressor Malfunction or R-12 Overcharge
HIGHHIGHOutlet air slightly cool. Bubbles in sight glass.Large Amount of Air of Air & Moisture in System
HIGHHIGHOutlet air warm. Evaporator outlet sweating and frost.Expansion Valve Stuck Open
(1) If equipped with a low refrigerant charge protection system, compressor operation may have stopped.
(1)If equipped with a low refrigerant charge protection system, compressor operation may have stopped.

A/C DIAGNOSIS W/GAUGES FOR SYS. W/INSUFFICIENT OR NO COOLING

Compressor Not Working

  1. Compressor clutch circuit open.
  2. Compressor clutch coil inoperative.
  3. Poor clutch ground connection.
  4. Fan belts loose.
  5. Thermostatic switch inoperative.
  6. Thermostatic switch not adjusted.
  7. Ambient temperature switch open.
  8. Superheat fuse blown.

Excessive Noise or Vibration

  1. Missing or loose mounting bolts.
  2. Bad idler pulley bearings.
  3. Fan belts not tightened correctly.
  4. Compressor clutch contacting body.
  5. Excessive system pressure.
  6. Compressor oil level low.
  7. Damaged clutch bearings.
  8. Damaged reed valves.
  9. Damaged compressor.

Insufficient or No Cooling; Compressor Working

  1. Expansion valve inoperative.
  2. Heater control valve stuck open.
  3. Low system pressure.
  4. Blocked condenser fins.
  5. Blocked evaporator fins.
  6. Vacuum system leak.
  7. Vacuum motors inoperative.
  8. Control cables improperly adjusted.
  9. Restricted air inlet.
  10. Mode doors binding.
  11. Blower motor inoperative.
  12. Temperature above system capacity.

Insufficient, Erratic, or No Heat

  1. Low coolant level.
  2. Incorrect thermostat.
  3. Restricted coolant flow through heater core.
  4. Heater hoses plugged.
  5. Misadjusted control cable.
  6. Sticking heater control valve.
  7. Vacuum hose leaking.
  8. Vacuum hose blocked.
  9. Vacuum motors inoperative.
  10. Blocked air inlet.
  11. Inoperative heater blower motor.
  12. Oil residue on heater core fins.
  13. Dirt on heater core fins.

Too Much Heat

  1. Improperly adjusted cables.
  2. Sticking heater control valve.
  3. No vacuum to heater control valve.
  4. Temperature door stuck open.

Airflow Changes During Acceleration

  1. Vacuum system leak.
  2. Bad check valve or reservoir.

Air From Defroster At All Times

  1. Vacuum system leak.
  2. Improperly adjusted control cables.
  3. Inoperative vacuum motor.

Blower Does Not Operate Correctly

  1. Blown fuse.
  2. Blower motor windings open.
  3. Resistors burned out.
  4. Motor ground connection loose.
  5. Wiring harness connections loose.
  6. Blower motor switch inoperative.
  7. Blower relay inoperative.
  8. Fan binding or foreign object in housing.
  9. Fan blades broken or bent.

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