It will operate without one, but you'll risk potential damage to your system and to your health and the health of your family, and that's just not worth it. One of the primary functions of the air filter on your furnace is to keep dust and other airborne particles from collecting on your furnace's inner components.
Technically, you can temporarily run a furnace without a filter. However, it's important to emphasize the word “temporarily” here. Running a furnace without a filter overnight, for example, isn't likely to cause problems, but you should never allow this to turn into a long term solution.
If you let it run very long without filtration, contaminants will build up. IAQ plummets when there is no filtration. Your family may experience health problems as contaminants and dust move through ductwork into the home. Mold spores could proliferate in the ducts, causing breathing issues.
If something happens and you have to pull your filter out for the day or even a day or two, it's probably not going to cause major problems right away. However, it's never a good idea to leave the filter out of your furnace for any longer than that.
You might wonder about the risks of running your AC without a filter, even temporarily. The simple answer is: not for long. Ideally, your AC should never operate without a filter for more than 6-8 hours. Going beyond this can negatively affect both your system's health and your home's air quality.
As a general rule, it is never a good idea to run your air conditioner or HVAC system without an air filter in place. Any amount of time spent doing so can lead to permanent damage and the possibility of needing expensive repairs.
If dust and debris get caught inside the air conditioner, it can clog up parts and prevent them from working properly. Plus, all the buildup of dust and debris can restrict airflow and cause your AC to overheat and shut down. It could even do permanent damage to your motor, which means you'd have to replace it.
A clean furnace filter will prevent large-sized debris from entering your actual heating system. A filter will catch things like pet hair, lint, dirt, dander, and more. Without it, all of these particulates could find their way onto and even into your furnace's most sensitive interior components.
If you were to use your home furnace without an air filter, all that dust and debris could get stuck in your system and cause a rather large buildup. Over time, these buildups can clog and damage your system. To protect and extend the lifetime of your system, we recommend only running your furnace with an air filter.
Can a dirty filter stop a furnace from working? Yes, without this furnace maintenance task of cleaning the filter, your furnace could require a premature replacement. If your maintenance list does not include replacing the filter, you're risking a lot.
Air Filters
Even though the furnace is not producing any heat while operating the a/c, it still delivers the cold air throughout your home with the same blower, and passing through the same air filter. This is why, regardless of the season, you should regularly change your air filters.
With a furnace blowing cold air, the first question you should ask is if the furnace has been turned ON. Two thermostat issues that could cause your furnace to blow cold air include (1) your thermostat is still set to COOL, not HEAT and (2) your thermostat fan is set to ON, not AUTO.
The first thing you'll want to do is shut off your HVAC system. You should always avoid changing furnace filters while running the heating system, as various types of debris can enter the furnace — and you certainly don't want that to happen.
Air filters that are overdue for a change are a common cause of HVAC system failure. Over time, dirt builds up in the heating and AC filters, causing components such as the motor to go into overdrive, which may eventually overheat your unit.
If the filter is still in good condition, light should shine through. If the filter is dirty or clogged with debris, the light will be obstructed, indicating it's time for a replacement. The presence of visible mold is another one of the dirty HVAC filter symptoms that indicates it's time for a replacement.
If your furnace is not blowing hot air, or is not operating at all, a component called the fan limit switch or high limit switch may have malfunctioned. You may also see an error message on your thermostat, or a blinking LED light on the furnace control board.
Your furnace can, technically, run without a filter. However, we strongly recommend you don't run your furnace without a filter for any length of time. With air constantly moving through your furnace and your home, dust and debris can quickly build up, even in a matter of minutes.
It Traps Dust and Allergens
You can probably guess what happens if there is no filter in the furnace. The filter helps maintain healthy indoor air quality by trapping allergens so they don't keep circulating throughout your house and get you sick.
One of the most common causes of a furnace shutting off unexpectedly is low airflow. If your furnace keeps turning off, check for issues such as: Dirty Air Filters. A clogged filter restricts airflow, causing the furnace to overheat.
At Quality Heating, Cooling & Plumbing, we often hear the question, “can you run a furnace without a filter?” While it is possible, it isn't the best idea. Without the filter, dust and dirt particles will accumulate in your air ducts, circulate in the air, and lead to a less efficient furnace.
The short answer: You can get away with running your AC without a filter for a short period of time. However, doing so for longer than 6-8 hours can hurt your system and decrease your home's indoor air quality.
Extreme Temperatures Temperatures outside being hotter or colder than expected can cause your system to run longer, cycling more air through your furnace or air conditioner. When more air is being pushed through the system by the blower motor man, naturally the filter is going to capture more dirt and clog faster.
Without an air filter in place, the engine may also be sucking dirt and debris in at the same time. This can cause damage to internal engine parts, such as valves, pistons and cylinder walls. The result is excessive oil consumption, poor engine performance, and eventually engine failure.
Your utility bills will go up.
When a filter gets clogged with dust and debris, it stifles airflow. That means your AC, furnace, or heat pump needs to work harder to reach the temperature you set on your thermostat. That means more energy is used, leading to higher utility bills.
Is my AC not working because of the filter? Potentially, yes. While there are a whole host of issues that could cause problems with your air conditioning system, a dirty air filter should be the first thing to check if your central air conditioning unit isn't working as properly as it should.