Condition
Outdoor Unit Not Starting
Indoor fan may run but outdoor condenser does not start. Capacitor, contactor, or defrost board.
Possible Causes
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
- Inspect for physical damage
Repair Options
Welded AC Contactor
Electrical arcing can 'weld' the contactor shut, causing the outdoor unit to run constantly.
Root Cause Analysis →Diagnostic Tests
- Ohm test
- Visual inspection
- Check coil voltage
Repair Options
Failed Defrost Control
A faulty board can cause the outdoor unit to freeze over in winter, blocking heat absorption.
Root Cause Analysis →Diagnostic Tests
- Check board LEDs
- Verify defrost sensor
- Test mode switching
Repair Options