Heat pump needs to heat in winter
October 19, 2015

Your heat pump has one job in winter: Keep you warm. Too bad it's failing spectacularly!

But why?

There are two possible issues:

  • Something is wrong with your heat pump.
  • Your body is playing tricks on you (no, seriously).

Let's explain each of these.

Why your body may be tricking you

Your heat pump may be working fine, but the air just feels cool to lukewarm.

Here's why: The average body temperature is around 98.6 degF. And, in cold weather, heat pumps tend to blow warm air out at 95degF.

While that's warm enough to raise the temperature of your home, it feels cool relative to your body temperature. This is different from a furnace, which can blast hot air over 100degF.

Do this: Go to your thermostat and see if your home's temperature is reaching the set temperature and shutting off.

If so, everything is fine.

If not, read the next section about common heat pump malfunctions.

7 common reasons a heat pump blows cold air

BEFORE READING FURTHER: Watch this video on how a heat pump works. It will make all our explanations make way more sense.

1) Dirty outside unit
In heat mode, the heat pump's outdoor unit uses liquid refrigerant to absorb heat from the air, and then transports that refrigerant inside to heat your home air.

However, the outdoor unit struggles to absorb heat from the air if dust, leaves/grass or a fence block airflow over the unit's refrigerant-filled coils.

The fix? Clean the outside unit and ensure that you're not surrounding it with a fence or cover.

2) Covered in snow or ice
Again, the heat pump needs to absorb heat from the outdoor air. Snow and ice will prevent that.

The fix? Shovel away any snow that's surrounding your heat pump's outdoor unit.

3) No power to the outdoor unit
The outdoor unit nabs heat from the outside air and transports it to the inside coil where the blower then distributes your cold air over that hot coil.

But if the outdoor unit has no power, your blower just blows cold air over a cold coil. Meaning no hot air for you.

The fix? Check the breaker box to see if the outdoor unit's circuit breaker was tripped. If so, reset it. If that isn't the problem, call a technician for help.

4) Auxiliary heat is malfunctioning
Below 40 degrees, your heat pump struggles to heat your home. So it relies on an auxiliary (AUX) heat coil (like the ones you see in a toaster) or a furnace to heat your home.

Therefore, if it's below 40 outside and the auxiliary heat isn't working, then your heat pump will just blow lukewarm or cool air.

The fix? A technician will need to repair the auxiliary heat.

5) Bad reversing valve
A reversing valve is the part that allows the heat pump to move from "COOL" to "HEAT" mode. If the valve is malfunctioning, your heat pump will only work like an air conditioner--just cooling.

The fix? A technician will need to repair the reversing valve.

6) Low refrigerant charge
To warm your cold inside air, the heat pump's outdoor unit uses liquid refrigerant to absorb heat from the outside air.

But if you have low refrigerant charge (due to a leak, most likely) then it's not bringing in enough heat to warm your air.

Think of it like trying to pour a thimble of hot water on a glacier. The amount of heat just isn't going to make a difference.

The fix? A technician will need to find the refrigerant leak and add a refrigerant charge.

7) Return duct leakage
Return ductwork is the series of pathways that return the cold air from your home back to the heat pump to be heated.

However, if those ducts are leaky and travel through unconditioned areas, like the attic, they will pull in cold, dusty air, making it difficult for your heat pump to properly heat the air.

The fix? A technician will need to find the leaks and seal them. Contractors call it "duct sealing".

Need a heat pump repair in Lawton, OK area?

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