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Understanding the capabilities and limitations of your heater during winter

February 17, 2021

Over the past few days San Antonio and surrounding areas have experienced abnormally cold weather conditions. With freezing temperatures forecasted to continue for the next twenty-four to forty-eight hours here is what you need to know about your heating system during the cold weather:

  1. Do I have a heat pump or a furnace?
  2. How does a heat pump keep my house warm?
  3. Why is my heat pump steaming? (Defrost mode)
  4. What is Aux heat? Can I use it to keep my home warm?
  5. What can I do if I don’t have any heat in my home?

Want a San Antonio professional to repair your heater? Our trusted technicians can quickly find what’s causing your furnace to blow cold air and fix the problem.


Do I have a heat pump or furnace?

To determine if your house has a heat pump or a furnace, first, locate the indoor unit. Next, look for a gas line or a flue pipe. If you do not see either you have a heat pump or an electrical system. Unless you live in a condo or mobile home you most likely have a heat pump.

How does a heat pump keep my house warm?

Unlike a furnace that produces warm air, a heat pump takes the heat out of the outdoor air and transfers it to the indoor coil via the refrigerant. The indoor air is passed over the indoor coil that has heated refrigerant and the heat transfers from the coil to the indoor air.

A heat pump is most effective when temperatures are above 30 - 40 degrees. If the weather gets below 30 degrees the system will require supplemental heating i.e., heating strips.

Typically, the electrical heating strips will activate during weather below 32 degrees or when the temperature in your home is 3 degrees below the temperature on your thermostat. You can manually turn on the electrical heating strips by turning on AUX heat on your thermostat.

Why is my heat pump steaming? (Defrost mode)

Moisture accumulates on the coil of the outdoor unit. During freezing conditions, the moisture turns into ice.

To keep the heat pump operating efficiently, the unit will defrost. The defrost mode can take up to 10 minutes. During this time do not be alarmed if you hear funny noises or see the outdoor unit steaming.

What is AUX heat? Can I use it to keep my home warm?

AUX heat is automatically activated if the heat pump cannot get the temperature inside your home within three degrees of the set temperature on the thermostat.


If you do not have any heat inside your home go to your thermostat and turn on AUX heat. Activating AUX or emergency heat will use the electrical strips inside the unit to produce heat for your home.

What can I do if I don’t have any heat in my home?

If you do not have any heat try the following:

  1. Make sure you have a clean filter
  2. Check the breakers
  3. Make sure all registers are open. Closing all the registers can force the unit to shut off due to inadequate air flow and pressure.
  4. Turn on AUX or emergency heat

Need a heater repair from a San Antonio tech?

We can fix whatever is causing your heater to blow cold air. When you hire a Jon Wayne technician, you can count on exceptional customer service and repairs done right—the first time.

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