Heat Pump Not Blowing Cold Air [Solved]

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Is your heat pump not blowing cold air?  If so, then you’ll find this article helpful in troubleshooting this problem. Summer comes with unbearably high temperatures and when you have a heat pump that is not blowing cold air, it can make you and your family really uncomfortable.

heat pump not blowing cold air
Two heat pump outdoor units

While there could be several reasons why your heat pump is not blowing cold air, the following are the most common ones:

  • Reverse valve is in heating mode (sometimes stuck there)
  • Bad thermostat wiring
  • Dirty air filters
  • Heat pump outdoor unit not turning on
  • Leaking refrigerant

Read also: Heat Pump Not Turning On [4 Easy Solutions]

Why Is My Heat Pump Not Blowing Cold Air?

1) Reverse Valve Is in Heating Mode

A reverse valve that stays or gets stuck in the heating mode will prevent your heat pump from cooling or blowing cold air into your home. A reverse valve or changeover valve is a device in your heat pump system that reverses the direction of the flow of the refrigerant.

The direction of the flow of the refrigerant determines whether you heat pump is cooling or heating. And this gives it the functionality to work both a heat pump and an air conditioner.

When you turn on your thermostat and you change the mode from cooling to heating, the reverse valve accordingly changes direction of the refrigerant. The other way round happens when you change from heating to cooling.

How can I fix a reverse valve that is not working?

If you think your heat pump’s reverse valve is not working or is stuck in one operating mode, start by first checking if your thermostat is switched to cooling mode.

And if its not, set it to ‘cool’ mode and wait to see if cold air will start blowing out of vents.

If you are using a Honeywell thermostat you will most likely need to remove the face of your thermostat to see a button for switching between heating and cooling.

And if you are using a Nest thermostat, you’ll need to swap the orientation between O and B in your thermostat’s settings. If your current orientation is on B change it to O, then turn on your thermostat. Wait for few minutes to see if cold air will start blowing out of vents.

2) Bad Thermostat Wiring

An incorrect thermostat wiring could also negatively affect how your heat pump works. If you recently had your thermostat installed, it’s likely that there is something wrong in your thermostat wiring. 

Typically, a heat pump thermostat will have an O/B terminal. This terminal controls the changeover valve. If the O/B terminal is not connected or is loosely connected, switching between the cooling and the heating modes will be a problem for your heat pump.

How do I fix a bad thermostat wiring?

If you have a thermostat that is not correctly wired, this problem can be fixed pretty quickly. Depending on the model and make of your thermostat, you’ll need to remove your thermostat off the wall and check the wiring behind it.

TIP: If you are working with wiring, you should turn off your system on the circuit breaker. This is for your safety and that of your system.

Once your thermostat is off the wall, ensure that there are no loose or hanging wires. Ensure also that the R and the Rc terminals are connected to wires. If there is only one of these two terminals which is connected, ensure that there is a short wire(jumper) between them.

Rc is power for cooling terminal and if it’s not connected, your heat pump won’t cool.

3) Dirty Air Filters

Actually, when your heat pump is not cooling your home and your thermostat has the correct settings, the first thing you need to check is the status of your air filters.

Dirty air filter
uncleaned air filter

Dirty and clogged air filters always cause problems with the normal working of your heat pump.  The Government recommends that air filters should be replaced once or twice in two months. But again, this can depend on the quality of your surrounding air and how often your system works.

What happens if you never change your air filter?

  • They will restrict the amount of airflow into your indoor handler. And this will in turn restrict air flow to the evaporator coils.
  • If air flow is restricted to your evaporator coil, then, only little air will be cooled. And this can stop your heat pump from blowing enough could air.
  • Clogged air filters will allow dirty air and other substance to bypass it and build up on the evaporator coil. This will cause ice formation on the surface of the evaporator coil and can cause the leaking of water.
  • And if the evaporator coil has lots of build up on it, the surface area for cooling the air will reduce and this will also prevent your air handler from blowing cold air.

How to tell if your air filter is dirty

If you don’t remember the last time, you had your heat pump air filters replaced, then its high time you did so.

Air filters are typically found at the return vents or at your heat pump’s indoor unit (air handler cabinet)

Open the return registers and remove the filter. Take a look at the air filter and if its color is like that of mud, then it’s definitely clogged and needs a replacement.

However, before getting a new filter, take note of the size of your air filter. Once you get a new one it, insert it and don’t forget to put back the cover.

TIP:  Never run your heat pump without an air filter.

Also read: Heat Pump Not Working [7 Easy Solutions]

4) Heat Pump Outdoor Unit Not Turning On

Another reason your heat is not blowing cold air is that your outdoor unit could be off. If the condenser is off, there won’t be heat transfer from your home to the outside air.

Check if the breakers are tripped or not. Locate the breaker for the heat pump outdoor unit usually labelled ‘air conditioner’. If its tripped, reset it accordingly and if its not tripped, go out and check if the condenser unit is running.

If breakers are not tripped and your condenser unit still can’t turn on, look at a small device called the disconnect on your wall (near refrigerant lines). Does it look intact? If it’s pulled out, then power can’t reach your condenser unit. To fix this, try putting back the disconnect in its position. This should restore power to your condenser.

If there is no noise coming from your condenser unit then the problem most like has to do with power.

5) Leaking Refrigerant

If your heat pump has run out of the refrigerant, no cooling will take place. While the refrigerant is designed to never run out, leaks in your system could cause it to escape. The refrigerant is an important component of your heat pump system.

fixing heat pump
A man recharging heat pump with a refrigerant

It works by absorbing heat from your indoor air as it passes through the evaporator coil. Then releasing the heat outside as it passes through the condenser coil of your heat pump outdoor unit.

If there are leaks, within your system, the refrigerant will leak out and your heat pump will not blow any cool air into your home.

Solutions for a leaked-out Refrigerant

If you think your system has run of the of the refrigerant, you’ll need to call a qualified HVAC technician to come and look at this problem.

A technician can come and investigate if there are any leaks and pinpoint them.

How Can I Make My Heat Pump Work Better?

There are few things that you can do to keep your heat pump working better and efficiently. These include:

 Changing air filters on time

Filters should not work for more than 3 months before changing them.

If you have pets around your home, you can change them even once a month.

Observing Regular Maintenance

To keep your heat pump working in great condition, the Government recommends that you observe regular HVAC tune ups at least twice a year. This does not only keep your system working at optimal, it also prevents unforeseen breakdowns which can be costly.

Keeping Your Condenser Unit Clean

Your heat pump outdoor unit also known as the condenser helps with disposing heat from your home. It has a network of coils where the gaseous refrigerant changes to liquid as it releases the heat.

Over time dirt, leaves and other objects can build up on your condenser unit making it hard for it to dispose heat. This can cause your unit to run longer and inefficiently to try and cool your home.

Final Thought

We hope this article has taught you how to deal with a heat pump not blowing cold air problem. Otherwise, if your heat pump continues with the same problem, it is best to call professionals for help. Thank you for reading.

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