Can a dirty filter cause AC not to cool?

If you find yourself in this situation, do not despair, however, as there may be some simple fixes you can make that will get you cool and comfortable again – without having to call a repair service.

First off, ask yourself a couple of questions:

• • How old is my air conditioner?
  • When was the last time my AC filter was changed?

  Modern air conditioning units last an average of 15-20 years, so if your AC is under that age and not keeping your house as cold as it should, it could be that the culprit is an old air filter.

  If you are wondering, can a dirty filter cause AC not to cool, the answer is absolute.

  Why is this? Well, a clogged filter will restrict airflow throughout your air conditioning system, thus preventing cool air from circulating through your ductwork. That means less cool air for you – and could be why, even though you set the thermostat at 74 degrees, your house only gets down to 78.

  A clogged air filter could also cause even more problems for your air conditioner in that may cause your entire system’s evaporator coil to freeze. This will have an even more detrimental effect on your comfort.

  The good news is that replacing your filter is a simple and easy task – one that anyone can accomplish. The only thing you will need is a new filter and the knowledge of where your air conditioner’s filter is located within the system. You will also need to know the correct size filter for your system.

  This can be accomplished easily enough, usually by a quick internet search to discover your system’s manufacturer requirements. You can then purchase a new filter at any home improvement store and get to work.

  NOTE: You should replace your home’s heating, ventilation, air conditioner (HVAC) filter at least once a quarter – more often than that if you have indoor pets – in order to keep it from getting clogged with pet hair and the dirt that they can bring into your home.

  Hopefully, this simple remedy will do the trick for you. However, if this does not help, try these other steps before making a call to a professional HVAC service company:

  Do a thorough check of your thermostat settings

  You, or someone in your household, may have accidentally changed the settings, or it is possible that the thermostat is still set for winter and therefore not prepared to kick on the air. So, in order to make sure it’s cooling at full strength simply set a temperature lower than your home’s current temperature reading. Give it a few minutes and see if the air conditioning kicks on at full blast.

  Ensure that all of your home’s vents are wide open

  Again, something simple here. However, you’d be surprised how many times this simple step can help you avoid calling a professional for central air repair. And poor flow through the duct of one area of a home will certainly affect the entire heating/cooling unit.

  Reset your cooling system

  If you are still not receiving strong air flow through your vents, you may also try switching your thermostat from “cool” to the “off” position and then switching the fan from “automatic” to “on.” Let the fan run for 30 minutes and then power up your air conditioning. The issue may resolve itself within 12 hours.

  If these options do not work, you will either need to undertake more in-depth DIY repairs or contact a service professional to diagnose and correct the problem.

  If you want to continue to try and fix the problem yourself, you will need the right equipment for the situation, including:
  

  • A multimeter
  • A voltage sniffer
  • And, of course, a set of screwdrivers and socket wrenches

  
  Now, let’s get going (again). Take a few seconds to listen to your condenser. Your unit’s compressor (located outside) and its fan should also be running – don’t worry, you’ll be able to hear its hum quite easily. If it is not humming, then that’s a sign that you’ll need to begin maintenance.

  One of the most common air conditioning failures is caused by a broken contactor/relay or a start/run capacitor – especially in units five years or older. Once you have purchased these parts, you’re ready to begin working your way through the unit.

  The first step in physical air conditioning repair is to properly ensure the power to the condenser is off — both for safety and to avoid causing more problems. To address this, first, switch off all breakers to the air conditioning/furnace unit and turn off your furnace switch. Now, open the electrical box next to your central air conditioning condenser and remove the disconnect box. At this point, use that voltage sniffer to ensure there is no power still flowing through the box. Inside the disconnect box are likely two cartridge fuses. Use your multimeter to determine if they are working. Success could be as simple as replacing those fuses.

  The next steps in air conditioning repair involve replacing the start/run capacitor, which is located inside the condenser’s access panel. The capacitor stores electricity and releases it to help compressor and condenser startup. NOTE: You will need to discharge the energy in the capacitor before removing it, which may be accomplished using an insulated handle screwdriver.

  The next step involves replacing the contactor – a mechanical relay within the control panel. NOTE: Ensure that you note where all the attached wires fit within the contactor and replace them like-for-like on the new contactor, or else it will not work.

  The final DIY step involves replacing the fan motor. Be sure to note the position of the fan blade and determine which end faces upward. NOTE: When routing the motor wires through the old conduit it is a good idea to secure the wires with zip ties so that the blade does not cut them when turned on.

  After replacing these parts, you will want to restart your central air conditioning unit. Know, however, that many units have built-in delay features that may take as long as 10 minutes to re-establish following a power outage. In the cases of energy-saving devices, it could take longer. And be sure you reverse your way through each step of the power-down process, replacing the disconnect block, turning the furnace switch “on,” triggering the circuit breaker, turning the central air conditioning “on” at the thermostat and setting the indoor temperature lower than the outside air temperature.

  If none of this works, shut down your cooling system altogether. If it is already crippled, you risk further damage by continuing to run the air conditioner. And if you find yourself in this position, it is best to contact a professional to correct the problem.