Condition
AC Running but Not Cooling
The unit is on and the fan runs, but air from vents is not cold. Refrigerant, coil, or airflow issue.
Possible Causes
Low Refrigerant Levels
A leak in the refrigerant lines prevents the system from absorbing heat efficiently.
Root Cause Analysis →Diagnostic Tests
- Check subcooling/superheat
- Leak test with nitrogen
- Pressure test
Repair Options
Dirty Evaporator Coils
Dust buildup on the coils restricts airflow and stops heat absorption.
Root Cause Analysis →Diagnostic Tests
- Inspect coil surface
- Measure temperature delta
- Check airflow
Repair Options
Blown Start Capacitor
The capacitor provides the electrical 'kick' needed to start the compressor; without it, the motor won't turn.
Root Cause Analysis →Diagnostic Tests
- Measure microfarads
- Check for bulging
- Test under load
Repair Options
Severely Clogged Air Filter
A dirty filter restricts airflow, putting strain on the blower motor and reducing efficiency.
Root Cause Analysis →Diagnostic Tests
- Remove filter and test
- Check static pressure
- Inspect for light pass-through
Repair Options