Outdoor unit will not start, control board shows E2, compressor and fan remain off even though thermostat is calling

Safety first: Turn off power to both indoor and outdoor units before opening panels. Do not attempt to add refrigerant or repair leaks without proper certification.

Steps:

• 1. Check indoor airflow: Ensure all supply and return registers are open. Replace a dirty furnace/air handler filter with the correct size and MERV rating.
• 2. Inspect evaporator coil: Remove the access panel on the indoor coil section. Look for ice buildup on the coil or suction line. If frozen, turn system OFF and set thermostat to FAN ONLY for several hours to thaw.
• 3. After thawing: Restore COOL mode and observe operation. If E2 clears and cooling resumes but the coil freezes again, there is likely a refrigerant or airflow problem.
• 4. Inspect low-pressure switch wiring: At the outdoor unit, locate the low-pressure switch on the suction line. Confirm the connectors are tight and wires are intact.
• 5. If E2 persists: The system may be low on refrigerant due to a leak or the switch itself may be defective. These conditions require leak detection and gauge readings—schedule a professional service call.