In this video, This Old House plumbing and heating expert Richard Trethewey shows how to prevent ice buildup from shutting down an air conditioning system.
Steps for Repairing a Frozen Air Conditioner
- Clean or replace the return-air filter to ensure it’s not obstructing the flow of fresh air to the air conditioner.
- Confirm that the size of the air-conditioning unit can accommodate the diameter and number of cool-air ducts.
- Remove the metal access panel to expose the evaporator coil.
- Check the size of the outdoor condenser unit. Typically one ton of cooling is needed for every 500 to 600 square feet of living space.
- If the condenser is too big for the house, it can cause ice to form on the evaporator coils and shut down the system.
- Pump out and collect the refrigerant from the existing too-large condenser.
- Disconnect the old condenser and cart it away.
- Install a new appropriate-size condenser.
- Connect the new condenser to the existing electrical power supply and refrigerant lines.
- Remove the old evaporator coil and replace it with a new coil that matches the tonnage rating of the new condenser.
- Reconnect the ductwork and seal the new evaporator cabinet at top and bottom with sheet metal strips and foil tape.
- Braze new copper connections to the refrigerant lines.
- Insulate the suction line.
- Connect PVC pipe to the condensate drain and then attach the pipe to a pump.
- Run flexible tubing from the pump to a drain.
- If necessary, add refrigerant to the new system.
- Turn on the air conditioner to ensure it’s operating properly.