Specifications

13
■ Too cool/warm and then too warm/
cool.
■ Faulty thermostat. Test continuity of thermostat and wiring. Replace, if needed.
■ Improper cooling anticipator. Check resistance of anticipator.
■ Improperly located thermostat. Relocate thermostat.
■ Airflow unbalanced. Readjust air volume dampers.
■ Not cool enough on warm days. ■ Dirty air filter. Inspect filter; clean or replace as needed.
■ Dirty indoor coil. Inspect coil and clean, if needed.
■ Not enough air across indoor coil. Check blower speed. Check duct static pressure and
filter.
■ Noncondensibles. Recover charge. Evacuate and recharge.
■ Recirculation of condensing air. Remove obstruction to airflow.
■ Infiltration of outdoor air. Check windows, doors, vent fans, etc.
■ System undersized. Refigure cooling load.
■ Wrong type of expansion valve. Replace valve.
■ Expansion valve restricted. Remove restriction or replace valve.
■ Undersized expansion valve. Replace valve.
■ Certain areas too cool, others too
warm.
■ Dirty air filter. Inspect filter; clean or replace as needed.
■ Dirty indoor coil. Inspect coil and clean, if needed.
■ Not enough air across indoor coil. Check blower speed. Check duct static pressure and
filter.
■ Infiltration of outdoor air. Check windows, doors, vent fans, etc.
■ Airflow unbalanced. Readjust air volume dampers.
■ Compressor is noisy. ■ Overcharge of refrigerant. Recover part of charge.
■ Broken internal parts. Replace compressor.
■ Broken valves. Test compressor efficiency. Replace if needed.
■ Expansion valve bulb loose. Tighten bulb bracket.
■ Loose hold-down bolts. Tighten bolts.
■ Heating Only—System runs—blows
cold air in heating.
■ Internal compressor overload open. Test continuity of overload.
■ Compressor stuck. Use test cord.
■ Shortage of refrigerant. Test for leaks. Add refrigerant.
■ Open element or limit on electric heater (heating only). Test heater element and
controls.
■ Overcharge of refrigerant. Recover part of charge.
■ Noncondensibles. Recover charge. Evacuate and recharge.
■ Broken internal parts. Replace compressor.
■ Inefficient compressor. Test compressor efficiency.
■ Faulty reversing valve. Replace valve or solenoid.
■ Faulty defrost control. Test control.
■ Faulty defrost thermostat. Test defrost thermostat.
■ Heating Only—Unit will not
terminate defrost.
■ Faulty reversing valve. Replace valve or solenoid.
■ Faulty defrost control. Test control.
■ Faulty defrost thermostat. Test defrost thermostat.
■ Heating Only—Unit will not defrost. ■ Faulty reversing valve. Replace valve or solenoid.
■ Faulty defrost control. Test control.
■ Faulty defrost thermostat. Test defrost thermostat.
Problem
No Cooling/Heating Cause/Test Method and/or Solution