Why is My Heat Pump Blowing Cold Air?

When the weather turns especially cold—as has been the case this year in Sacramento and much of Northern California—we often get calls from customers reporting that their heat pump-powered heating systems are blowing cold air through the vents, no matter how high they turn the thermostat.

This is a common complaint, and in order to explain what’s going on, first we have to backtrack and explain what a heat pump is.

How a Heat Pump Works

Classic furnaces work by generating heat—usually by burning natural gas or powering an electric heating element—and then using that heat to warm air that is blown through a heat exchanger.

Heat pumps are a different beast altogether. Heating up air uses a lot of energy and is financially costly. Heat pumps don’t have this problem because they don’t use an energy source to produce heat. Instead, they’re essentially two-way air conditioners, capable of removing heat from a home and emitting it outdoors, or vice versa. This versatility is what has made them increasingly popular: they’re relatively simple, and eliminate the need to install separate heating and cooling systems.

Whereas traditional heaters rely on heat generation, heat pumps work by transferring heat. Their operation relies on a key truth about heat: It wants to be evenly distributed, and will move from areas of high warmth to areas of low warmth. This is why your home warms up in the summertime, while the winter weather seems to suck the heat right out of your home.

Heat pumps take this process and crank it into overdrive, extracting heat from cool and even cold air. Most homes use air-source heat pumps, which run outside air through a series of coils that extract heat energy. This energy is transferred to internal air that is passed through the heat pump and then blown back into the home. Meanwhile, the outside air is redirected back into the outside environment as a blast of icy cold air.

The neat trick with heat pumps is that in summer, this process is easily reversed, allowing the same mechanism to instead transfer heat out of your home, cooling it in the process.

Why a Heat Pump Will Blow Cold Air

Here’s the downside of a heat pump: The warmth of the air it produces is entirely dependent upon the outside temperature. Generally speaking, a heat pump will produce air that is about 55 degrees warmer than the outside air. This isn’t a problem when it’s 55 degrees outside—your system will expel air that’s a toasty warm 110 degrees or so.

But when the winter weather drops to 40 degrees, that means your system will blow air that is about 95 degrees. If it drops to 30 outside, your system will blow 85 degree air, which is much cooler than your skin temperature. As a result, the air will actually feel cool against your skin.

However, this air is almost certainly warmer than the desired temperature of your home (unless you like living in a sauna), and thus will successfully maintain that temperature. You just won’t be able to warm your feet on a toasty warm vent like you would in a home heated with a traditional furnace.

Heat Pump Problems

It is important to note that occasionally, heat pumps will go through a defrost cycle, during which the unit will blow air that is truly cold. But this will only go on for a couple minutes, and won’t affect the overall temperature of your home.

However, if your heat pump blows cold air for more than a couple minutes every hour or so, then your system isn’t working properly. Check to make sure that the air intake isn’t blocked, the ductwork is properly connected, and the filter is clear. If there are no obvious issues, then it’s probably time to give your local heating and air company a call.

Common issues that require professional intervention include:

  • Low refrigerant
  • Internal debris buildup
  • Valve failure
  • Stuck in air conditioning mode
  • Compressor not operating
  • Failure of the deicing unit

If your heat pump isn’t working properly or has failed altogether, give Gilmore a call. We’ll fix it right the first time, so you can rest easy knowing that you and your family will be living in comfort again in no time!