Why Is My Heat Pump Blowing Hot Air in Cooling Mode?

Last month in Chattanooga, TN, the Anderson family came home after a long day at the lake expecting to cool off indoors to find hot air pouring from their vents. With temperatures sitting at 96°F and rising, their heat pump was blowing warm air even though it was set to cool. Panicked and sweating, they called us for emergency HVAC service. Unfortunately, their situation is far from rare. If your heat pump is blowing hot air in the middle of summer, here’s what could be causing it:

Thermostat Settings or Wiring Issues

One of the most common and overlooked causes is incorrect thermostat settings or wiring problems. Sometimes, the system is accidentally switched to “heat” mode or suffers from miscommunication between the thermostat and the heat pump.

Double-check your thermostat settings and replace batteries if needed. If the issue persists, an HVAC service technician may need to inspect the wiring or recalibrate the device.

Reversing Valve Malfunction

The reversing valve is the component that allows a heat pump to switch between heating and cooling modes. If it’s stuck or malfunctioning, your system could remain in heating mode, even in the peak of summer. A faulty reversing valve requires professional repair or replacement, but catching it early can prevent excessive energy use and discomfort.

Low Refrigerant Levels

Low refrigerant can prevent your heat pump from properly absorbing heat inside your home, resulting in warm air blowing from your vents. Leaks in the refrigerant line are often the culprit. If your system is low on refrigerant, a certified service technician can locate the leak, repair it and recharge your system so it functions efficiently again.

Dirty Coils or Clogged Filters

Dirty evaporator coils or clogged air filters restrict airflow and heat exchange, causing your heat pump to underperform or blow warm air. Regular maintenance, including coil cleaning and filter replacement every one to three months, can help prevent this issue and keep your Chattanooga home cool during the hottest weeks of summer.

A heat pump blowing hot can result in many dangers inside your home during a summer heatwave. Act now by contacting Dalton Heating & Air to have your heat pump repaired and its efficacy restored.

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