Common Reasons Why Your A/C Is Blowing Hot Air

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One of the first things you may do when your A/C is blowing hot air is check the thermostat setting while thinking to yourself, “There must be some mistake.” Sometimes we set the thermostat to heating instead of cooling. If that doesn’t solve the problem, there could be something wrong with your system. Try to diagnose and fix the problem these troubleshooting tips.

Ice Buildup on the Evaporator

The evaporator coil is located in the indoor air handler, usually just above the furnace in an upflow system. Cold refrigerant flows through the evaporator and extracts heat from your home. If airflow is obstructed, such as from a clogged air filter, ice begins to form on the coil, further obstructing airflow. The problem snowballs from there, and soon you’ve got an evaporator encased in a block of ice. What can you do?

  • Turn off the A/C and let the ice melt before changing the air filter.
  • Clean the evaporator with a foaming coil cleaner when the ice has completely melted. Debris and grime can also block heat exchange enough to cause ice accumulation.
  • Turn on the air conditioner and keep an eye on the evaporator for the next 48 hours. If the ice returns, call your HVAC professional. There may be a problem with refrigerant charge, compression or the electrical system.

Dirty Condenser and Compressor

If the evaporator and air filter are fine, check the outdoor half of the cooling system where the condenser coil and electric compressor are housed:

  • With a hose, thoroughly spray the sides of the unit. A dirty condenser obstructs heat release, and a dirty compressor can overheat and malfunction.
  • If you hear humming or buzzing coming from the outdoor unit, the compressor is malfunctioning and may not be processing refrigerant correctly. A clicking noise indicates a faulty electrical relay. Call your HVAC technician for either problem.

For more troubleshooting tips when your A/C is blowing hot air in your greater Cleveland home, or to schedule an A/C maintenance appointment, contact Geisel Heating, Air Conditioning & Plumbing today.