Unit powers on but compressor never starts; fan may run continuously without heating.

Safety first: Isolate power and discharge capacitors before touching electrical components.

• Listen for contactor: When a heat demand is present, listen for a click from the compressor contactor. No click may indicate a control or contactor issue.
• Inspect contactor: Check for burned or pitted contacts and loose coil wires.
• Check capacitors: On models with start/run capacitors, look for bulging or leaking capacitors and replace if defective.
• Professional testing: A technician should measure compressor winding resistance and verify control signals from the PCB to the contactor or inverter.