Ruud air conditioner runs briefly then shuts off; diagnostic display or LED indicates E2.

Safety first: Shut off power at the breaker and disconnect before opening panels. Refrigerant work must be performed by a licensed technician.

• Step 1 – Check air filter and indoor airflow: Replace a dirty return air filter. Ensure all supply and return registers are open and unobstructed. Poor airflow can cause low suction pressure.
• Step 2 – Inspect indoor evaporator coil: Remove the access panel on the Ruud air handler or furnace coil box. If the coil is heavily dusted or iced over, turn the system OFF and set the thermostat to FAN ON to thaw the coil. Once thawed, clean the coil with a non-rinse evaporator coil cleaner following label directions.
• Step 3 – Inspect low-pressure switch wiring: At the outdoor unit, locate the low-pressure switch near the suction line. Check for loose or broken wires and corroded terminals. Repair or reconnect as needed.
• Step 4 – Look for signs of refrigerant leak: Oil stains on refrigerant lines, at the service valves, or around the evaporator coil can indicate a leak. Do not attempt to tighten flare or braze joints yourself.
• Step 5 – Call a technician: If E2 persists after restoring proper airflow and verifying wiring, a technician must check refrigerant pressures, locate leaks, and recharge the system according to Ruud specifications.