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Why is my AC not blowing?

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Last Updated on April 26, 2019


ac not blowing

The seasonal temperatures are here. You know the air conditioning system has been turned on, yet you’re just not feeling the comfort you would expect. The disappointing lack of cool air coming through the air conditioning vents prompts you to ask yourself, “Why is my AC not blowing?”

The most common causes of an AC not blowing are related to:

  • fan problems
  • power issues
  • thermostat problems
  • clogged filters
  • blocked registers
  • dirty coils
  • ductwork leaks & blockages
  • system design flaws

Most would agree that no one wants to live or work in an oppressive climate with warm temperatures and stagnant air. There are many reasons for airflow problems, so let’s troubleshoot the possible reasons for your AC not blowing.

Top 9 reasons for an AC not blowing

1. Power problems

Though finding your AC not blowing in a heat wave, may send you into a panic mode, there’s no reason to get alarmed. The cause for your AC not blowing could be a simple one that can be solved at no cost or little cost.

When unbearably hot and humid weather hits, most tend to crank up their air conditioning 24/7, which puts a strain on the power grid. Consequently, power outages are not uncommon during a heat wave. If there has been a power outage, it is conceivable that the clock or timed settings on your thermostat need to be reset.

Also, check to make sure the power to the unit is on and circuit breakers are not tripped.

If it seems you’ve got an electrical problem, read more about that here: Why is my air conditioner tripping the circuit breaker?.

2. Thermostat issue

It may sound silly, but it’s advisable to check to make sure it is set correctly; some digital thermostats can be tricky to program. Do people in your space like different temperatures? Another possibility is someone who doesn’t like it as cool as you do, may have turned up the thermostat.

The thermostat also could be faulty or its batteries drained, so it can’t send proper signals to your system. The result: your AC not blowing.

3. Clogged filters

It’s so simple, yet so many of us neglect changing filters regularly. Filters are a vital component of an AC system and could be a reason for an AC not blowing. It’s the filter’s job to remove dust and contaminants from the air before it gets trapped in ducts and equipment. If the filter is clogged, air will have difficulty passing through. A clogged filter could cause coils to freeze because your system will be forced to work longer and harder.

Learn more: Why and how to change an air filter

4. Make sure vents and registers are not blocked

All too often, we are not mindful of the location vents and registers when we move furniture around a room to capture the best seating design or TV viewing angle. Well, if the sofa is set in front of a vent, then airflow will be blocked.

5. Clean the condenser unit

An AC not blowing sometimes is caused by a dirty condenser unit. The condenser unit, which is usually located outside, is exposed to dirt, soot, debris, tree branches, twigs, leaves and all types of weather. Make sure the condenser and its environs are clean; otherwise it will have difficulty accessing air and could lead to the system overheating. The task of cleaning a condenser unit, which is powered by high voltage electricity and contains hazardous chemicals, should be left up to a HVAC professional.

6. AC not blowing? It could be the ductwork or other system design flaws

It is critical that your AC system has been designed correctly and its ducts installed properly. A well-designed system will feature ducts that deliver the right amount of air to every room. Too many bends/turns in the ductwork will reduce flow. Possibly, the interior space of your building has been rearranged and walls relocated. The original ductwork may not be a good fit for the redesigned space. It is advisable to have a HVAC expert assess the design or your system. A few ductwork changes could go a long way to improving airflow.

Too much of a good thing is often not a good thing. You probably wouldn’t think an AC system that’s too large could be behind our AC not blowing problem, but the truth of the matter is an oversized system can cause airflow issues just as an undersized system can provide disappointing cooling results. If your air conditioner is too powerful, it will cycle on and off more frequently and not stay on long enough to remove humidity from the air. Though the AC not blowing isn’t exactly the issue, the stuffy air can make it feel like it is not blowing.

7. Leaks and blockages

Again, it’s the ductwork. If your ductwork is leaking through holes and cracks, the air is not making it to where your need it most; in your living and work space. It’s not all that unusual for ducts to be riddled with holes sometimes caused by rodents who squeeze their way in from outside. Also, ducts can become clogged by birds, insects and other small creatures building nests.

8. Soiled coils

As previously mentioned, your AC coils (both indoor and outdoor) play a critical role in the release of heat. If they are caked in grime, they will not be able to absorb or release heat and will have to work harder and harder to cool your rooms. Eventually, the dirty coils can lead to airflow problems with the AC system straining to meet cool air demands established by thermostat settings. Dirty coils can be a reason for an AC not blowing.

9. AC not blowing? Maybe the fan is not fantastic

Blower fans push air through the ducts of your AC system. If the fans are covered in dust and dirt, the blades are likely not rotating at optimum speed, which will hamper airflow. A failing blower motor will not do its part to push air through the ducts and in your space.

Repair or replace your failing AC?

While many of these problems are small fixes, some of them could come with hefty price tags for repair. If your system is older, you may need to decide if it’s worth investing a large amount to fix a system that may break down again soon. Compounding that problem in the fact that the refrigerant used in many older units (called R22 or Freon) is being discontinued in a couple of years. If your system uses R22, chances are you’ll need to replace it before long anyway. (Learn more: How will the R22 Refrigerant Phase Out Impact Your AC)

Here’s a resource that can help you make the best repair vs. replace decision:
Should you repair or replace that broken HVAC equipment? Download the complete guide.

How to prevent problems like your AC not blowing

As you can see, your AC not blowing can be caused by a variety of reasons and those operational issues can cost you in terms of comfort and efficiency. Though you can address some of the smaller glitches, most of the problems are best handled by an HVAC expert.

Better yet, do not wait to be cast into a crisis mode and hire a reputable HVAC company, like Arista Air, to perform routine preventative maintenance. By having regular maintenance you can reduce the operational cost of your system and save on repairs.