Unit powers on but compressor never starts; only fan runs and no cooling occurs.

Safety: Unplug the unit. High voltage and stored charge in capacitors can be dangerous.

Steps:

• Listen for compressor: When cooling is selected, listen for a deeper humming sound from the compressor. If you only hear the fan, the compressor is not starting.
• Check capacitor: Access the electrical compartment and locate the compressor run capacitor. Discharge it safely, then test capacitance with a meter. Replace if out of spec, bulged, or leaking.
• Test compressor windings: With power off, measure resistance between compressor terminals and to ground. Open windings or shorts to ground indicate a failed compressor.
• Control relay: If the compressor and capacitor test good, the compressor relay on the main control PCB may not be energizing. Inspect for burned relay contacts and replace the board if necessary.
• Refrigerant issues: If the compressor runs but there is still no cooling, the sealed system may be low on refrigerant or restricted. This requires a licensed HVAC technician.