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What you'll need:
TOOLS
- Soft brush or compressed air
- Protective gloves
- Spray bottle
- Towel
SUPPLIES
- Replacement air filter
- Protective gloves
- Spray bottle
- Coil Cleaner
If your AC unit is frozen, don’t just let it go. Ice on your air conditioner unit usually points to blockages that can damage your system from restricted airflow. Instead, learn how to fix a frozen AC unit by checking and cleaning components and, in some cases, having a pro come take care of the rest.
Prepping to Unfreeze Your AC
While the steps involved with de-icing an AC unit are pretty straightforward cleaning tasks, you will need to account for the time it takes to thaw the ice—this could take up to 24 hours. Ice on your AC unit outside may be caused by colder-than-usual refrigerant liquid. Turning the thermostat off will stop your air conditioner from sending cold refrigerant to your outside unit.
After removing the ice, you can diagnose and troubleshoot more easily. The most common reasons for ice on your AC are:
Dirty air filter
Dirty evaporator coil
Low coolant levels
Cleaning your unit is a simple afternoon DIY, but if your troubleshooting efforts don’t solve the problem, you may need to call an HVAC professional to investigate further.
But let’s not get ahead of ourselves. More than likely, you can resolve this issue yourself.
Turn the Thermostat from Cool to Off
The first step to unfreeze an AC unit is allowing the ice to thaw. You’ll want to take care of this before calling in a pro—if needed—as there is quite a bit of waiting involved.
Find and switch off the correct breakers in your box, then turn off the power switches at your furnace and your outdoor condensing unit. This will prevent the system from accidentally turning back on. Once you’ve completely disconnected power to the unit, check for leaks or stains, which may be signs of a bigger problem that requires a repair specialist.
Wait for the ice on the evaporator coil to thaw—this may take up to 24 hours. While you wait, proceed to the following steps.
Turn the Fan Setting On
If the weather is warm and your system has a fan-only setting, you can opt to keep the system running with the cool setting off and the fan-only setting on. Do not turn the fan setting to auto.
With the fan setting on, observe the system for about an hour while it blows warm air over the air conditioner’s frozen coils. Look for the following:
No airflow, despite the fan running
Condensate dripping while the AC isn’t running
Sweating on the sheet metal near the coil
These issues are signs of problems that won’t be solved by simply thawing out the system. You’ll need to call in a pro.
Resist the urge to scrape or chip the ice as you channel Yukon Cornelius. This will only end up damaging your unit’s components. Once the ice thaws, use a towel to gently soak up any pooled water or condensation on the unit.
Examine Your Air Filters
Ice on your AC unit often points to blockages in airflow. While you wait for the unit to thaw, check for a dirty or clogged air filter that might be blocking airflow and causing the unit to become a glacier. With the power completely off, check your unit’s filter for dust or dirt and replace it if needed.
Even a thin layer of dust or dirt on an air filter can suffocate your AC and restrict the free flow of warm air through the system. When your air conditioner doesn’t get enough warm air flowing over its evaporator coils, the liquid refrigerant inside gets much colder than it should be, leading to the buildup of ice on the unit.
You’ll need to wait until your AC unit has completely thawed before testing to see if the filter was the issue. Once unfrozen, turn your unit on and run the air normally, watching it carefully for a few days. If ice returns, you’ll need to troubleshoot further.
Check the Evaporator Coils
If you changed your air filter recently and still see ice on the AC unit, your evaporator coil may have collected too much dust, dog hair, caked-on grime, and who knows what else. Like a dirty filter, a dirty coil can also obstruct airflow, causing your unit to overwork and freeze.
With the unit off, don a pair of protective gloves, and spray the coils with a commercial coil cleaner. Gently but thoroughly clean the coil with a soft brush or compressed air. Do not use anything scrubby or abrasive on your evaporator coil, as this can damage it.
Once your coils are clean, use a spray bottle filled with warm water to remove any remaining cleaner. Wipe dry the cleaned coils with your towel, removing all moisture before reconnecting the AC unit to power. If you cannot clean your coils or notice a more significant issue,hire a local HVAC technician to evaluate the problem.
Observe Coolant Levels
Ice on your AC lines might also indicate low refrigerant. Contact a local HVAC company to check for leaks and, if need be, perform a freon leak repair. This type of AC repair costs between $225 and $1,600 depending on the leak’s location and severity.
Reset the System
When troubleshooting AC problems, you should always have the system fully shut off at the breaker. Once you’re done checking for issues, confirm that all ice has completely thawed off the system before restarting it.
Start up the unit and the blower again, then monitor for the next few days. If you find ice on the AC unit again, you might have a more complex issue that requires help from top local HVAC specialists.
DIY vs. Hiring a Pro
While you can change filters and clean an AC unit yourself for under $40, these strategies might not be enough to permanently unfreeze the system if a bigger issue is at play. Most AC professionals charge a flat rate for service calls, averaging $100 to $200 for one to two hours of work. Other pros might charge an hourly rate, about $50 to $150 per hour.
If you’d like to get your AC inspected or under a tuneup, you’ll pay about $100, according to HomeAdvisor.
How to Prevent Your AC Unit From Freezing
Once you’ve pinpointed the cause of your unit turning into an icicle, maintain a consistent AC service schedule to keep components clean and to prevent ice on your AC unit due to freon leaks. This will also help you save money on AC costs by ensuring your system is running at its maximum efficiency. Otherwise, be kind to your system by running it consistently and leaving all important repairs up to the pros.
Below are some additional tips to prevent future ice buildup on your AC unit:
Change your air filters regularly
Avoid running your air conditioning when the temperature outside is cold
Clean your unit’s evaporator coils periodically to prevent buildup
