AC Blowing Hot Air Inside and Cold Air Outside [Fixed]

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Is your air conditioner blowing hot air inside and cold air outside? If so, then you are in the right place.  Summer comes with high temperatures and the last thing you want to do is turn on your ac system and discover that it’s not blowing warm air inside instead of cool air.

outside ac unit blowing cold air

 There are a few reasons for your ac system to work in reverse and these include the following

  • Thermostat set to heat
  • Thermostat orientation settings
  • Reverse valve issues
  • Malfunctioning control board

Read also: AC Condenser Unit Blowing Cold Air Outside [Solved]

Now let’s dive into details and see how each of these issues mentioned above can affect how your air conditioner works.

Why Is Air Conditioner Blowing Hot Air Inside and Cold Air Outside?

If your ac is blowing cold air outside and warm air outside, there could only be a few reasons for this problem, and these include the following:

1. AC Set to Heat Instead of Cool

An air conditioner that is set to heat instead of cool could be the reason for your ac blowing warm air inside and cold air outside.

Most modern air conditioners come with both heating and cooling functionality. And if you accidently swap the two functions, that could result in your ac blowing warm air inside and cold air outside.

This is so because air conditioners work by absorbing heat from air in one environment and disposing it to the air in another environment. With that in mind, when you set your air conditioner to cooling mode, cool air should blow in your home while your ac should eject warm air outside.

But how do you know that you have set your ac too cool mode? Look at your thermostat, if you can see a snowflake icon then your ac is definitely in   cool mode.

However, setting your air conditioner to heat mode will cause it to blow warm air inside. And if it blows warm air inside, you should expect cool air to blow out of your ac outside unit.

2. Thermostat Orientation Settings

Another thing that could cause your ac to blow hot air inside and cold air outside is because you haven’t changed the orientation on your thermostat. This often happens if you use a heat pump for cooling and heating.

Depending on the thermostat model you have, you’ll need to verify that your orientation settings are correct. These settings work between cooling and heating. Check your thermostat manual and you should have instructions on how to set heat pump orientation correctly.

If you verify that the orientation settings are correct, but your ac is still blowing warm air, there could be a problem with a reverse valve.

3. Reverse Valve Issues

A reverse valve helps to switch between heating and cooling mode of your air conditioning system. In short it changes the direction of flow of the refrigerant so that when you need cooling, your system will cool. And so that it will heat when you need heating.

Over time, the reverse valve can malfunction and get stuck in one position. And if it sticks in the heating position, that means that your air conditioner or heat pump will not be able to cool your home.

A defective reverse valve will prevent your ac to cool your home even if you adjust settings on your thermostat or remote control.

If you want to know for sure that your reverse valve is defective, try setting your thermostat to heat and when warm air starts blowing in try setting your thermostat to cool and lower your temperature to a point lower than your current room temperature. If warm air continues blowing out after several means, that could mean there is a problem with your Reversing valve.


If you suspect that your ac reversing valve is defective, its best to call in a professional to come and look at your system. With necessary tools, an HVAC professional should be able to provide you with a solution quickly.

Also read: Air Conditioner Outside Unit Not Running [Solved]

4. Malfunctioning Control Board

A control board is found inside your air handler or furnace and is a controller of your HVAC system. It receives instructions from your thermostat and relays it to other parts of your HVAC system. If the control board is defective or not responding, it can send wrong signals to you HVAC system and that could be the reason your ac is blowing warm air inside and cool air outside.


If you think your control board could be the reason for this problem, try resetting it. A control board can be reset by turning off and on your HVAC system. You can do this by resetting the circuit breaker (at your home’s electrical box) for the air conditioner and the air handler.

Otherwise, if the problem continues after resetting the whole system it’s time to call professionals.

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Final Thought

Now that you know the commonest reasons for your air conditioner blowing hot air inside and cold air outside, we hope you have fixed this problem. In case your ac problem is not fixed after going through our tips, we recommend that you call in your local HVAC professionals.

Need Professional AC Repair? Use Our Database to find a qualified HVAC repair service in your neighborhood.
(Call Now: 1-877-342-2087 )

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