Troubleshoot Air Conditioning Problems

Common Symptoms & Solutions

A-1 Guaranteed team member examining thermostat

Homeowner Solutions to Air Conditioning Problems

By: Tony, Past A-1 Guaranteed Service Manager

As a service technician, I encounter a wide variety of problems with air conditioning systems out in the field. Some are serious, others are a quick fix that can be resolved by the homeowner with some research and ingenuity, and other issues fall in-between.

What are the symptoms you are experiencing?

Fan comes on, unit not blowing cold air:

Let’s start with the thermostat. Check the “Fan” switch. It should usually be set in the “Auto” position. If it is in the “On” position, it will simply circulate the air (not heat or cool), and the fan will continue to run like this until it is placed back into “Auto.”

Now, make sure the thermostat is turned to “cooling” with the set-point turned below the room temperature. When turning it on, you should hear a small “click” as the system goes to turn itself on. If the cooling cycle was just on, there may be a delay as a protection measure. This is to prevent damage to the equipment from being rapidly turned on/off several times in a row.

Also, a majority of thermostats installed take a few batteries. These should be replaced about once a year. If they are aged, they might not be providing enough power to let the thermostat switch into cooling (or heating) mode! Also, older batteries may have leaked corrosive acid into the thermostat and caused its failure.

If you have checked all of this at the thermostat and you have heard it click into cooling, let’s walk outside to your A/C unit. Do you see the fan on top spinning? If not, go to your electrical panel or sub-panel and reset the breaker. If all is fine there, then there may be a more serious issue that you should call a qualified and licensed professional.

Outdoor unit comes on, but airflow weakens the longer the system runs:

Look at your air filter – it may be installed in the largest register(s) in your home, or in the furnace itself. This should be replaced every 1-3 months, depending on things like location of the intakes, pets, allergies, etc. Many filters that I encounter in the field haven’t been replaced in nearly a year, some haven’t been replaced in several years! Not only does this affect the quality of air that you breathe, but a dirty filter causes not enough air to move through the system and places undue stress on such things as your fan motor, furnace’s heat exchanger, and effects the heat transfer process of the refrigeration cycle.

Install a new filter in your system and mark the date on it, as well as make a note in your calendar to replace it in a few months. If your filter is clean, and you notice that your airflow is still weakening the longer the system runs, there may be an additional issue that should be checked by a qualified professional.

Outdoor and Indoor units do not come on:

If you have already checked what is mentioned, and neither component comes on, go to your furnace or air-handling unit. Verify that it is plugged in and has power to it. Also, make sure that the doors to the unit are properly installed. A loose door will disengage a safety switch in the unit and not allow either component to come on – this protects the customer from reaching into the unit and exposing themselves to live electrical components and/or a moving fan blade. If you are still encountering issues after having check all of this, call a qualified professional to investigate.

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