Skip Navigation

How to Fix an Air Conditioner that Blows Hot Air

In the dead of summer, the last thing you need is a broken air conditioner blowing hot air into your home. If your air conditioner is blowing warm air, follow these steps to troubleshoot so you can get right back to comfortable temperatures.

What you'll need:

  • Soft brush. This will help you clear debris fromthe condenser coils.
  • Vacuum with attachment. Use this to lift away residue the brush removes from the condenser coils.
  • New air filter. Optional, but it should be replaced every 30 to 90 days.

Step 1: Rule out setting errors.

Sometimes your air conditioner dials and switches can get bumped or accidentally set on the wrong options. Before you start to take everything apart, check all the settings to ensure that your air conditioner is set to cool and not to vent. If it is set wrong, simply flip the switch back to the proper position and see if the unit cools again.

basement room with air conditioner

Step 2: Replace your air filter.

Dirt that obstructs the airflow in your air conditioner can cause it to overwork and malfunction or burn out over time. Cleaning off the unit may help it blow cool air again. If it's been more than 30 to 90 days since you've replaced your filter, you should replace it. Even if it hasn't been that long, you should clean the filter with a soapy rag to prevent dirt from building up.

replace your air conditioner air filter

Step 3: Clean condenser coils.

Condenser coils can be cleaned using a soft brush and a vacuum. Turn off and unplug the air conditioner, and then use a soft brush to loosen residue and clean it up with a vacuum cleaner attachment.


Step 4: Check refrigerant levels.

If your air conditioner has the proper settings and is fully cleaned, low refrigerant is the most likely cause of your hot air problems. Over time, your air conditioner will use up its stores of refrigerant. In many states, it is illegal to purchase and handle refrigerants for a DIY repair. Since these substances can be very dangerous to work with, it is typically best to leave this job to a service technician. In addition, your service technician can check the unit for potential leaks, ensuring your continued safety and fixing your hot air problems.