Hansberger Refrigeration Blog: Your AC Repair Resource

If Your HVAC Unit Overheats, That Could Be Trouble. Learn How to Prevent It.

An overheating HVAC unit can cause expensive damage and may even present a fire hazard in certain cases. Usually, an automatic safety switch incorporated in the unit senses the overheating condition and shuts it down, or a circuit breaker trips. The result is the same: You are inexplicably deprived of heating or cooling until the problem’s diagnosed and resolved. Here are some typical causes of an overheating HVAC unit and what needs to be done to fix it:

A Dirty Filter

Low system airflow due to a dirty, clogged air filter may cause either a furnace or a central air conditioner to overheat. This is because the strangled airflow makes the system run almost constantly, eventually overheating vital components. Replace the air filter every other month during the heating season and every month during the summer cooling season.

Closed or Blocked Vents

Closed or obstructed HVAC vents in rooms reduces overall system airflow which, in turn, may overheat the furnace heat exchanger or the A/C compressor. This can trigger system shutdowns or cause expensive damage such as a cracked heat exchanger. Ideally, all supply and return vents in all rooms should be open all the time to support optimum airflow.

Blower Fan Issues

Low furnace or A/C blower output caused by a worn-out fan motor or a slipping drive belt can also cause airflow-related issues, including overheating. A qualified HVAC service tech can isolate the problem and restore proper airflow.

Low Refrigerant Charge

Air conditioner refrigerant carries heat extracted at the indoor evaporator coil outside to the condenser coil. If insufficient refrigerant is circulating, ice may form on the evaporator coil, eventually obstructing all airflow. This overheats the compressor — the most expensive component in the system — and may cause irreparable damage. Low refrigerant is almost always caused by a leak somewhere in the system, which must be pinpointed and repaired by a professional HVAC technician.

For more information about preventing or resolving overheating HVAC issues, contact Hansberger Refrigeration and Electric Company.