Clogged Air Filter When the filter becomes dirty, this can block airflow and cause the evaporator coil to get too cold, which can lead to a frozen AC unit. As a general rule of thumb, many HVAC professionals recommend replacing the air filter every 90 days.
A dirty filter can cause the unit to freeze which results in loss of air flow, loss of cooling and water present around base of unit.
What happens if your HVAC filter is dirty? A dirty HVAC filter restricts airflow, which can lead to poor system efficiency, increased energy costs, and wear and tear on the unit.
An AC freezing up because of a lack of airflow can happen in two ways. The first occurs when warm air isn't reaching the evaporator coil, resulting in the coil getting colder and colder until it freezes. The second is that cold air doesn't come into your home, leaving the air in place and allowing it to freeze.
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.
Increased Energy Consumption
A dirty filter forces your AC system to work harder to maintain a cool temperature, leading to an increase in energy consumption. If your utility bills have spiked without any apparent reason, a thorough cleaning of your filter might be all it takes to rectify the issue.
Whether you've confirmed for certain that you have frozen evaporator coils, or you just suspect it, you need to turn off your A/C. Then, your coils should be able to defrost, taking up to 24 hours to thaw out. You can also safely dry out the coils with a hair dryer.
1st Step: Turn Your HVAC Unit Off.
Even if it's sweltering outside, you still need to turn OFF your air conditioner! Running a frozen air conditioner will wear out parts much faster, and could overheat your unit. Worn parts are bad news for the most expensive piece of your HVAC unit—the compressor.
How Often Do I Need to Change Out My Air Filter? Generally, most air filter manufacturers and HVAC companies recommend changing your air filter every 90 days, or 3 months. That can change based on where your home is located (ex. dusty, dry climates), if you have any pets, and the age of your system and equipment.
To fix a frozen AC unit, turn it off to let the ice melt. Check and replace the air filter if it's clogged, and ensure the vents are clear. Also, clean the coils. If the issue persists, call a professional to inspect for refrigerant leaks or a malfunctioning component.
Many disposable air conditioner filters should be replaced rather than cleaned, as cleaning with water can lead to possible mold issues. Clean the coils and fan of the AC regularly, using a canister of condensed air to blow away dust and buildup.
A Dirty Filter Can Be Worse Than No Filter
The longer you use your air filter, the dirtier it becomes.
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.
Then, change the fan setting from 'auto' to 'on. ' The fan will slowly defrost the system. Once your air conditioner is ice-free, you can turn it back on and reset the fan to auto (This may take an hour or more).
Not only does this force the air conditioner to work harder to do its job, but it has the potential to cause the coil to freeze over because the refrigerant inside will remain too cold. Ice on the coil will continue to build up until the AC isn't removing any heat from the air.
While an air conditioner should normally cycle on when it senses an increase in temperature, and off when it has sufficiently cooled the room off, short cycles can occur when you have a dirty air filter.
A new, clean new air filter keeps your HVAC unit running smoother and running longer, extending its useful life.
Yes, you should turn off your AC if it's not cooling. Continuing to run a malfunctioning AC can strain the compressor and other components, leading to more severe and costly repairs. If there's a refrigerant leak or airflow issue, running the AC can cause the evaporator coils to freeze, compounding the problem.
To defrost your HVAC unit, you want to begin by turning off your thermostat and turning your fan on. Let the fan run over the next few hours to allow your unit to defrost.
Turn the AC off, it will eventually thaw itself. Leaving the indoor fan running to help blow warm inside air over the coil helps this happen faster.
In the past, when my coil froze, I ran the heater briefly 2–3 minutes, followed by the fan to melt everything. Seems to work great for me.