No cold air
- Low refrigerant from a leak.
- Compressor not commanded on due to pressure, electrical or HVAC control issue.
- Condenser fan not operating or airflow restriction.
- Blend door fault giving warm air even when evaporator is cold.
Common A/C issues and what they normally mean.
Automotive air-conditioning faults need leak-aware testing. Refrigerant work must be handled correctly and should not be treated as an endless top-up.
ARCtick AU068264ABN 92 694 005 760Leak-aware process
Cold then warm
- Evaporator icing due to low charge, airflow issue or sensor fault.
- Compressor clutch air gap or coil heat failure on clutch-type compressors.
- High-side pressure rising from poor condenser airflow.
- TX valve or control valve behaviour outside expected range.
High pressure
- Overcharge, air/non-condensables in system or poor condenser cooling.
- Fan speed fault, blocked condenser fins or debris between condenser and radiator.
- Restriction after condenser/drier or incorrect refrigerant/oil amount.
Low pressure / poor cooling
- Low refrigerant from leak.
- Compressor not pumping properly.
- Expansion valve/orifice issue.
- Temperature sensor or pressure sensor data stopping compressor command.
Air-con diagnostic checklist
- Confirm customer complaint: no cooling, weak cooling, intermittent, noise, smell or demist complaint.
- Check cabin filter and airflow first. Poor airflow can mimic refrigerant faults.
- Record ambient temperature and centre vent temperature.
- Check compressor command, clutch/control valve operation and fan operation.
- Inspect condenser, hoses, service ports and visible oil staining.
- Use pressure readings only with context: ambient temperature, engine speed, airflow and compressor state all matter.
- If the system has lost refrigerant, locate and repair the leak where practical before charging.
Important refrigerant note
A leaking A/C system should not be repeatedly topped up. Refrigerant handling is regulated and should be performed by a suitably licensed technician. Mobile Motive lists ARCtick Licence AU068264 for automotive A/C work.
Common customer explanations
| Customer says | Likely direction | What to verify |
|---|---|---|
| “It just needs a regas.” | Maybe low refrigerant, but why did it leave? | Leak signs, pressure state, service port caps, condenser damage. |
| “It cools at highway speed only.” | Condenser airflow or fan issue. | Fan command, fan speed, condenser blockage, high-side pressure. |
| “It clicks on and off.” | Low charge, pressure switch behaviour or clutch/control fault. | Pressure data, compressor command, clutch gap/coil, wiring. |
| “One side is hot.” | Blend door/dual-zone HVAC issue or low charge depending layout. | Vent split, actuator movement, evaporator temp, scan HVAC module. |