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.
Without a filter, indoor air contaminates are inhaled by you and your family or left to create a buildup in your furnace or ductwork. To piggyback off what we wrote above, if left unfiltered, indoor air contaminates can make a home inside your ductwork.
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're concerning air conditioning filters, the solution is no. Air filters cannot work better when dirty, once it's clogged with dirt; it blocks the free flow of air into the cooling system and out of the air conditioner. The air filter must be cleaned of dirt and dust.
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.
Not only does an air filter trap particulates and protect your AC, but filters also keep debris out of your air ducts. Without a filter in place, these contaminants are free to travel throughout the ducts and may settle there, again possibly negatively impacting health due to the worsened indoor air quality.
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.
As mentioned previously, running your air conditioner without a filter can lead to severe problems. It could lead to decreased comfort and permanent damage to your HVAC system, which may result in hefty repair bills.
If you don't change your furnace filter, it can become clogged with dust and other particles. This can cause your furnace to work harder to circulate air, leading to increased energy consumption and potentially damaging your furnace.
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.
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.
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.
The main purpose of an air filter is to protect the HVAC system especially the blower motor and evaporator coils. The longer you run your AC or furnace without one, the more dust and other debris can get pulled into the system leading to premature system failure due to the extra strain.
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.
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.
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.
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 clogged air filter can also increase the chances of a fire, further advancing the safety concerns in this home. Clogged air filters prevent furnaces from running properly and reduce the life of the system. The blower, heat exchanger, burners and other components are all crucial for heating your space.
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.
A clogged air filter can cause more harm than good. During the day, your AC should cycle on and off, but a dirty air filter can make those cycles more frequent than they should be. Cycling is not only noisy, but it also wastes energy.
Decreased air quality is the most common problem when AC's are run without a filter. Dust will not settle down in a room with an AC running continuously without a filer. This will eventually lead to the clogging of the unit.
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.
First, check your filters and coils for dirt and debris that may be impeding airflow. Once you've cleaned the filters and coils, run the air conditioner with just the fan so that the ice accumulation can melt off. If the AC still doesn't blow cold air, it could be that refrigerant levels are too low.