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The office staff members answering customer calls at ACE Home Services often check off this concern: “Air conditioner not blowing cold air,” which gets our HVAC technicians in the truck and on their way. Among HVAC companies in Phoenix, this is the most frequent call for help. In the high heat of summer, and in the slightly cooler days of fall, we still get the call. If you’re facing air conditioner not cooling problems, continue reading to see your options.

7 Most Common Causes for A/C Not Blowing Cold Air

A few of the most common causes for faulty air conditioning can be handled by the homeowner. Most, though, require the friendly professionals of ACE Home Services for safe, reliable servicing and air conditioner repair. if you air conditioner is working but not cooling, check the following.

ACE Home Services - Why Is My Air Conditioner Not Blowing Cold Air? - Filters

#1 Dirty Air Filter

Most air conditioner filters are disposable; requiring they be changed monthly. Some types, though, are permanent, meaning they have to be thoroughly cleaned at least annually (more often is better). Disposable air filters get dirty, fast. This is the sort of air conditioning repair that a homeowner can take care of with a little routine maintenance.

During air conditioning season — which, in Phoenix, Arizona, can be nearly year-round — the central air conditioner’s filter gets a huge workout. The volume of air blowing through it is substantial. Think about it: Your entire home’s volume of air should be changed (cleaned, cooled and recirculated) several times an hour.


When to Change Home
During seasons of high HVAC use, such as summer, it is very important to change your air filter approximately once a month. Failing to do so could end up costing you in the long run.
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All that air is real matter, even if you cannot see it. The mix of gases in your household air includes some very tiny particulates (grainy solids) and airborne pollutants. Unless you pay for expensive ultraviolet lamps that zap organics, your central air conditioner’s air filter is your only safeguard against damage from this debris.

Central air conditioner filters are not intended to clean your home’s air for your benefit; their primary purpose is to protect the internal mechanisms and moving parts of your A/C unit. A side benefit is cleaner air for you and your family to breathe.

A dirty air filter can do its own damage to your central A/C. The dirty filter slows down airflow, which means cool air has a hard time getting to your family and the living space.

See also: Which A/C air filter is right for my home?

Other Issues Relating to Dirt & Dust

    1. Dirty air ducts:

If the filter is clogged and dirty, your ductwork also is dirty, so dirty air is being pumped out, however feebly, into your breathing space.

    1. Inefficient cooling:

Dirt on the filter often means dirt on the cooling coils, causing them to build up frost while decreasing your cooling power

    1. Family health:

Dirty air can make allergy symptoms worse, subject your family to germs and even make pets sick.

    1. High energy bills:

Inefficient air conditioning from a dirty filter can cause your system to run for longer periods, more often, which just increases your electrical use and drives up the power bill.

The homeowner’s simple remedy to this is to either replace the disposable filter every month during cooling season or have a professional HVAC technician install a deep-media filter (a type of high-quality permanent filter). Permanent central air conditioning filters generally offer far greater performance than the big-box store’s disposable filters of spun fiberglass.

ACE Home Services - Why Is My Air Conditioner Not Blowing Cold Air? - Coils

#2 Dirty Cooling Coils

Your central A/C unit consists, generally, of two parts: an interior part with cooling coils, and an exterior part with a fan and condensing coils. Both coils need cleaning, but the interior cooling coils require significantly more attention, since they are in a moist environment. Mold, dust, allergens and other pollutants can build up quickly on the interior evaporator coils, robbing your system of cool air and shortening your air conditioner’s lifespan.

Most homeowners will opt for professional cleaning, since this involves taking apart the air conditioner cabinet. If you choose to do this cleaning yourself, expect the job to take about an hour. Products are available at big-box home improvement stores and hardware stores specifically to clean air conditioner evaporator (cooling) coils. Most are no-rinse expanding foams that clean the coils, then drip into the condensate pan.

ACE Home Services - Why Is My Air Conditioner Not Blowing Cold Air? - Parts

#3 Faulty Parts

A failing A/C compressor is a common complaint in the Phoenix area. This is because our air conditioning systems get long workouts, measured in total days per year and total hours per day. Faulty parts may be faulty through no fault of the manufacturer – they just wear out, and you no longer get cold air from your system.


Compressor Failure Checklist
A compressor that is faulty or on its way out can definitely cause your air conditioner to blow warm air. To know if you have a compressor problem, click here to see the signs.
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A failing compressor, though, manifests itself in many ways:

    • The compressor motor may be seizing:

This causes an electrical fault that stops the motor. Look for the reset button; if it has popped out, allow the motor to cool and then push the reset button.

    • Hesitant starting or quick on/off performance:

A wire may be loose; if you are comfortable working with electricity, turn off power to the system and check all wiring connections.

    • Incorrect compressor pressure:

Your system has pressure gauges to give you this information, but most homeowners will call on an HVAC contractor to deal with this.

    • Loss of cooling:

Often a sign of compressor age, even if the unit is only a few years old. The gauge ports can be replaced, or the entire compressor may need replacement.

ACE Home Services - Why Is My Air Conditioner Not Blowing Cold Air? - Electrical

#4 Electrical Issues

Your home’s air conditioner depends on a steady supply of clean electricity without spikes and dips. It requires its own circuit breaker, so other on/off motors do not rob it of power. Within the A/C system itself, wires run everywhere.


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If your air conditioner isn’t blowing cold air, keep an eye out for any electrical issues that could be the cause. Signs include a breaker flipping, visible damage to wiring, or capacitor stuttering.
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These are the most common electrical issues that can rob you of cold air:

    • Faulty circuit breaker:

If your system keeps tripping the circuit breaker on your home’s main panel (most A/C systems have their own electrical panels, either breakers or fuses, near the unit), have a professional inspect the circuit breaker.

    • Bad capacitor:

Capacitors help air conditioner motors start and keep running by storing electrical energy for sudden discharge. These capacitors can wear out or get damaged, robbing your system of needed power.

    • Bad wires:

Wires can fray and corrode; look for this especially on the outside portion of our system. Again, electrical issues like wire replacement are best left to professionals.

ACE Home Services - Why Is My Air Conditioner Not Blowing Cold Air? - Refrigerant

#5 Low Refrigerant Levels

Your home’s air conditioner has a fairly small amount of refrigerant keeping the lines cool and transferring heat to the outdoors. For every ton of cooling power, around two to four pounds of environmentally friendly refrigerant should be in the lines.


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If you suspect that your air conditioner is blowing warm air due to refrigerant levels being low, click here to discover the three warning signs to look or listen for.
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Several performance issues and signs point to low refrigerant:

  1. Loss of cold air inside
  2. Higher-than-usual indoor humidity
  3. A/C running for long periods
  4. High electricity bills
  5. Ice buildup on the interior coil and refrigerant line leading outside
  6. Hissing or bubbling noises

Low refrigerant levels almost always mean a leak in the line somewhere, and simply adding refrigerant is illegal. The leak must be found, repaired and then the line refilled.

ACE Home Services - Why Is My Air Conditioner Not Blowing Cold Air? - Outdated

#6 An Outdated System

Central air conditioners have limited lifespans. In the Phoenix area, expect a solid decade of strong cooling power from your system, followed by around five years of diminishing cooling and rising repair costs. Eventually, you will need to consider replacing the entire system.

This is actually a good thing, as modern A/C systems are far more efficient than their predecessors. This means your old central air conditioner could be costing you a lot of money on electricity, repairs and annual servicing. Consider replacing your home’s air conditioner to save money over the life of your new system.

Only you can decide the tipping point between buying a highly efficient central air conditioner (the higher the Seasonal Energy Efficiency Ratio — SEER — the more efficient the system) and your return on investment. If you plan to remain in your home for another 20 years, a high SEER system can save you a lot of money.

ACE Home Services - Why Is My Air Conditioner Not Blowing Cold Air? - Thermostat

#7 Broken Thermostat

Surprisingly, a frequent cause for an air conditioning system not blowing cold air is a broken thermostat. The thermostat on the wall of your home is either battery-powered or hard-wired. If the thermostat takes batteries, changing them every year will keep the unit functioning normally in most cases. Today, thermostats come in an array of options, including WiFi smart phone-operated models.


Troubleshooting Thermostat Article
If you suspect that your thermostat is the reason why your air isn’t blowing cold, click here to see how to troubleshoot it at home with four easy steps.
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You can also check to see if you have a broken thermostat:

    • Short-cycling:

Your air conditioner is constantly starting and stopping, possibly because the thermostat’s settings are wrong or its circuitry is faulty.

    • Dust:

Lightly clean off the interior of the thermostat to remove dust that can interfere with sensors.

    • Wires:

Are all wires secured to their terminals?

Anything else — such as taking the wires off their terminals to connect them to test for a response from your air conditioner system — should be done by a professional HVAC repairman, because losing thermostat wires inside your home’s wall is an easy “oops” for the amateur.

Contact ACE Home Services to Make Your Air Conditioner Blow Cold Air Again!

We hope our tips have taught you how to fix an air conditioner not cooling. But when all else fails, it’s time to call the pros.

For all your Phoenix home’s air conditioning needs, turn to the one HVAC company that prizes customer service above all else; contact ACE Home Services today by clicking or calling (602) 943-2000. In our area, plenty of HVAC repair companies respond with “Replace it,” no matter how big or small the problem.

At ACE Home Services we value long-term customer relationships. Speak to a representative today to see how we can help get your air conditioner blowing cold air again.

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