Can You Run The AC In The House When It’s Cold Outside?

December 1, 2019

In short, the answer is no. Our perspective is not to run your AC when the outdoor temperature is below 50 degrees. Many people like to run the AC to cool the house when they sleep not only to reduce the temperature but normally to circulate the air around the bedrooms.

What Happens to a System When It’s Below 50 Degrees Outside?

In the refrigerants R22 & 410A, there are lubricants. As the outdoor temperature decreases, the viscosity increases so it does not flow as easily. The internal pressures drop, and the system is working harder to pump the freon around the system.

The refrigerant in the system will be at a freezing point or below which can/will lead to ice build-up on the evaporator coil on the indoor unit. The freezing and thawing of a coil will lead to early failure/damage of the evaporator coil.

The outdoor condenser unit will start to ice up on the copper lines and condensing coils. The more ice there is, the more restricted the airflow becomes. Again, leading to a short lifespan of the equipment.

At temperatures below 40F, the compressor in the outdoor unit may start to make strange noises. That can mean that the refrigerant is entering the compressor as a liquid rather than vapor. The system is designed to run with refrigerant vapor which is compressible versus liquid which is not. This can cause damages to the internal components of the compressor.
The exception is the variable speed AC system. If you have a variable speed system like a Trane VX18 or XV20, the unit can slow down the compressor to compensate for the lower temperatures and pressures.

Why Does The Air In My House Get Stuffy If I Don’t Run The AC?

If the air is not circulating, warm air can build up in a room and reduce comfort. We suggest trying to run the HVAC system in fan only or circulate mode to move air around the house.

How Do I Cool My House If I Can’t Run The AC?

If your home is warmer than you would like when the weather is cold, we suggest turning on a ceiling fan, running your AC in “fan” mode to circulate the cooler air, or opening a window for a short period of time.

What If Running The Fan Only Or Opening The Windows Doesn’t Work?

If circulating the air with the HVAC system fan or opening a window does not work for your home, there are other solutions. First, have a technician come to your home to investigate the issue. There could a lack of airflow to a particular room or a ductwork problem. Other solutions include adding a dehumidifying unit to your HVAC system, adding a heater to the outdoor unit’s compressor, or installing a low ambient temperature kit to the system.

Give us a call or send us a text if you have any questions at (469) 444-2001!

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