How do you diagnose an air conditioner

Air Flow

No air flow

  1. Inspect blower motor
  2. Inspect blower motor resistor
  3. Inspect fuse
  4. Inspect A/C climate control
  5. Inspect connectors
  6. Inspect harness
  7. Inspect hvac box for

Cooling

No cooling

  1. Inspect A/C switch
  2. Check refrigerant level
  3. Inspect clutch relay
  4. Inspect PCM/BCM/ECM
  5. Inspect A/C pressure switch
  6. Inspect compressor clutch coil
  7. Inspect compressor clutch
  8. Inspect compressor clutch air gap
  9. Inspect condenser
  10. Inspect condenser fan
  11. Inspect radiator fan
  12. Inspect evaporator temperature control devices
  13. Inspect temperature sensors control devices
  14. Inspect climate control
  15. Inspect in cabin temperature sensors
  16. Inspect sun load sensors
  17. Inspect power steering pressure sensor

Bad Smell

  1. Check cabin air filter
  2. Check evaporator core
  3. Check hvac box drain tube
  4. Check re-circulation air door /actuator
  5. Check hvac box seals

Noise

Clicking noise

  1. Check A/C clutch
  2. Inspect A/C clutch relay
  3. Inspect cycling switch
  4. Inspect refrigerant level
  5. Inspect evaporator temperature sensor

Squealing

  1. Check drive belt
  2. Check belt tensioner
  3. Check compressor for seizing

Grinding

  1. Check compressor
  2. Check compressor clutch
Other helpful tips

Replace the receiver driver with every A/C service.

Replace cabin air filter annually

Ensure that service valve caps are in place at every A/C service.

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