Thermostat calls for cooling but only the indoor blower runs; outdoor unit does not start

Safety: Turn off power to indoor and outdoor units before inspecting wiring.

• Check low-voltage fuse: Inspect and replace the low-voltage fuse on the furnace/air handler control board if blown.
• Inspect condensate safety switch: Locate any float switch in the condensate drain line. If the pan is full of water, clear the drain and reset or replace the switch.
• Check Y wiring continuity: With power off, disconnect the Y wire at both thermostat and furnace/condenser ends and test continuity. Replace the cable if open.
• Verify condenser control wiring: Ensure the two low-voltage wires from the furnace board to the outdoor unit are intact and properly connected.
• Call technician: If wiring and switches are intact but the condenser still does not start, an HVAC technician should inspect the contactor, capacitor, and compressor.