Home AC Not Blowing Cold Air [Solved]

With your home AC not blowing cold air on a hot day or night, the unbearable hot summer temperatures could really make your life difficult. And if you are asking yourself, ‘why is my ac not blowing cold air?’ There are a few things that can prevent your air conditioner from blowing cold air. These include:

  • Little or no refrigerant charge
  • Thermostat Issues
  • Bad Thermostat wiring
  • Dirty air filters
  • Dirty or covered coils
  • Leaky ductwork
  • Reverse Valve issue
Home ac unit not blowing cold air
Woman feels hot because ac is not blowing cold air

Luckily, for most of these issues, you can fix them yourself without calling in HVAC repair services. But for a few others, you will need to call in licensed HVAC professionals to come and have a look.

For us to have a clear understanding of how certain issues can affect the normal working of an AC system, lets briefly look at how it works.

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

How Does a Home AC or Heat Pump System Work?

An air conditioner and a heat pump system work on the same basic principle your home refrigerator runs. They all use a chemical known as refrigerant. Nearly all modern cooling systems use halogenated chlorofluorocarbons (HCFCs) as the refrigerant. I don’t want to go into details here, but you can find useful resources here.

An AC system typically has an indoor unit and an outdoor unit. The indoor unit comprises of a coil called evaporator and an outdoor unit has a condenser coil.

So, this is how your AC system works:

  • The pump (compressor) pushes the refrigerant through a network of coils. The liquid refrigerant evaporates in the evaporator coil as warm indoor air comes in contact with the coil.
  • As the refrigerant evaporates into gas and goes into the condenser coils, it carries with it heat from the indoor air.
  • This heat is transferred to the outdoor air as the refrigerant condensers back to liquid. That’s why, its important not to have any objects covering your outdoor unit.
  • The cycle continues until the set temp point is reached.

That is basically how your central ac system works. Now let’s dive into details of common issues that can negatively affect the normal working of your cooling system.

7 Reasons For Home AC Not Blowing Cold Air

The following are possible reasons for your AC unit not blowing cold air:

1. Little or No Refrigerant Charge

The refrigerant, the chemical used in your air conditioning system can escape from your HVAC system if there are leaks.

The refrigerant is responsible for absorbing heat from your indoor air and releasing outside through the outdoor condenser unit.

A leaking refrigerant is a common cause for an ac not not cooling your home. This is what will happen when you have little or no refrigerant in your air conditioner system:

  • There will be no medium to absorb heat from your home, so the blower fan will not blow cold air, but just air of the same temperature as your indoor air.
  • Your compressor will overheat when there is no refrigerant. If your AC unit is not recharged with a refrigerant for a long time, it will cause trouble with other components of your central air conditioning system

Solutions to a leaking refrigerant

It can be hard to pinpoint the leaks in your HVAC system unless the leaks are bigger and are easily visible. But in most cases, they are too small and may need a HVAC professional to use special tools to pinpoint the leaks.

In this case you will need to call HVAC repair services to come and take a look.

2. Thermostat Settings

After having checked out with your refrigerant charge and things with it look good but your ac does not blow cold air, it’s time to check your thermostat.  Some common issues with your thermostat include:

  • Your thermostat not set correctly: Actually, the first thing you need to check when you notice that your air conditioner is not blowing cold air is the thermostat setting. You need to make sure your thermostat is set to cool. Then adjust the temperature a little lower than you room temperature. Now go to your vents and feel if cool air has started flowing in
  • Thermostat not correctly programmed: If you are one of the homeowners that are using a programmable thermostat, it’s possible that your thermostat was not programmed correctly. Because you can set different temperatures of the day, its very easy to make a mistake. Counter check your programmed thermostat for any mistakes.

3. Bad Thermostat Wiring

If you are facing a home ac not blowing cold air despite your thermostat been set to cool, the problem could be with your thermostat wiring.

This is especially the case if you missed out something during your thermostat installation.  Usually, each primary function of the thermostat has its own terminal connected to a specific wire.  

Other times, it’s the loose wires in your thermostat’s wiring that could be causing the problem. For wiring references of your AC wires to the thermostat, head over to the control board of your HVAC system and look at the wiring designation of the terminals.

To check the status of your thermostat wiring, remove it from the wall.For some thermostats you might need a screw driver to do this. Make sure that the following terminals are connected:

S – Indoor and Outdoor Wired Sensors

Y – Compressor Stage 1 (Cooling)

Y2 – Compressor Stage 2 (Cooling)

G – Fan

C – Common

For more instructions, try going through your thermostat’s user manual. If this is something that you can’t carry out yourself, it is in order to call in a professional HVAC guy.

4. Clogged Air Filters

Just like in any other HVAC system, air filters are important in ensuring that your AC system works efficiently. But if your air filters are dirty, they will negatively affect how your air conditioner works.

Dirty or clogged filters will restrict the amount of air flow into your air conditioner and this could affect cooling efficiency of your air conditioner.

Clogged air filters will also block the passage of air and because of this, air can bypass your filters and find its way into your ac unit. And this is what will happen:

  • Air that bypasses your filters will deposit dirt on the evaporator coils. When the coils are covered with dirt and other objects, this will reduce their heat absorbing capabilities and this will prevent your indoor air from been cooled as expected.
  • Your air conditioner will overwork to try and cool your home and will result in more electricity bills.

Air conditioner filters need replacement or cleaning regularly. Government recommends replacing air filters at least once in 2 months. However, depending on the condition of your surrounding air or if your keep pets, you may need to replace or clean your air filters more often.

Also read: AC Heat Mode Not Working [5 Easy Fixes]

5. Dirty Or Covered Outdoor Condenser Unit

Heat pump not turning on
Heat pump outdoor unit

Your air conditioner’s outdoor unit has condenser coils, compressor and a condenser fan. The condenser fan draws air into the condenser coils and takes away the heat that comes from your home to the outside air.

When there is foliage near the condenser unit, your coils could quickly become dirty and covered with leaves and debris. This will prevent your condenser coils from disposing the heat to the outside air. Thus, this will make your air conditioner’s cooling inefficient. So, clogged air filters could be the reason for your ac unit not blowing cold air

You can clean the coils by rinsing then with a hose or vacuuming it.

6. Tripped Breakers

Another possible reason your AC is not blowing cold air is a blown-out fuse or a tripped circuit breaker. Usually, a heat pump has separate breakers for both the indoor and the outdoor unit.

Mostly likely, it’s the outdoor unit that will trip the breaker and while power to the condenser unit will cut off, your indoor fan can keep blowing air that is not cool.

Head over to inspect the circuit breakers and if possible, have a look at the power switches for both the indoor and the outdoor unit.

The power switch for the indoor unit it typically installed near the door while for the outdoor unit, near the area where refrigerant lines get into your home.

If any of the switches is off, switch it on and observe if your air conditioner will start blowing cold air.

7. Leaky Ductwork

While you maybe troubleshooting your air conditioner, the problem could be a leaky ductwork. Ducts distribute the air throughout your home but when they have leaks or disconnections, the cooled air will escape from your ducts before making it into your living spaces.

If no proper job was done during the installation of the ductwork, they will soon start to have issues. And if rodents find their way into your attic, they can cause damage to your ductwork.

Finding the leaks in your ductwork can be hard sometimes that you will need to call HVAC repair services to come and help. But if you are DIY kind of a person, you can still try to find loose connections or leaks. Sealing these leaks should not be hard.  You can use something like mastic tape to seal them off.

Malfunctioning Reverse Valve Could Cause Home AC Not Blowing Cold air

Issues with the reverse valve could cause heat pump not cooling.  The reverse valve is a component of your heat pump system that is responsible for switching the flow of the refrigerant so that your heat pump can work as a heater and an air conditioner.

After years of use, the reverse valve can malfunction and get stuck either in the heating or cooling mode.

To know for sure if the problem is with your reverse valve, try running your heat pump in the heat mode. If it works fine in heat mode but does not work in the cool mode. Then the reverse valve could be the culprit. In this case it is no wiser to call in HVAC repair services.

How To Prevent Unforseen AC Problems

Regular maintenance should be done on your air conditioning system to avoid unforeseen break downs. Generally, it’s a good practice to have HVAC tune ups at least twice a year.

Air filters can work for about 2 months because they can be changed. Regular maintenance will keep your central AC system working efficiently.

If you hear any strange noises coming from your air conditioning system, do not ignore them, try to find out where the noises are coming from.

Same with smells, unusual smells from your HVAC system could mean a problem. Never ignore these signs. If they go without been checked, other components of you HVAC system could be wearing out. Eventually this can result in unforeseen and costly breakdowns.

Final Thought

There are few reasons for your home AC not blowing cold air but the ones we provided in this article are the most common ones. Generally, your HVAC system should last you many years but when it starts having troubles every now and then, it can become costly repairing it often. It is better to get a new HVAC system. This is especially where the cost of repair is more than half the cost of getting a new cooling system.



Leave a Comment