When your air conditioner is on, it is pumping freon through the evaporator coils, which means they're going to stay cold and the ice won't melt. Without the coils operating, the ice should melt. It should take about 24 hours for the ice to melt, but it could be longer if your unit is covered in a solid block of ice.
Your AC blower motor pulls in warm air from inside your home, and blows it over the refrigerant coils that make up the evaporator. How long will it take for your AC unit to thaw? It can take up to an 1 hour or 24 hours to unfreeze your air conditioner. It all depends on the extent of the ice buildup.
Turning the HVAC fan to ON will force it to blow warm air over any frozen coils—which will speed up the defrost process. Make sure it's actually set to ON and not to AUTO. Automatic settings cause the fan to cycle—starting and stopping over and over again. You want continuous, non-stop airflow over the frozen areas.
For your first step, turn the air conditioning system off and give the frozen evaporator coils a chance to thaw out. You can do this by shutting the unit off at the circuit breaker. Left to its own devices, it could take up to 24 hours for the coils to thaw completely.
Getting Rid of the Ice
It's a relatively easy thing to get rid of the ice. You just have to turn off the unit and let it defrost. You can also leave the unit on and run just the fan to help melt the ice. At any rate you will have to let the ice melt before troubleshooting the system.
Ice can form on your air conditioner or heat pump in any weather if the refrigerant inside it falls below freezing. Ice on your HVAC unit wastes energy, and it can cause damage or failure. If you have ice on your outdoor unit, turn your system off, check for problems, and contact a professional to repair any damage.
When an air conditioner is low on refrigerant or charged incorrectly, the coils containing the refrigerant get too cold, causing ice to build up on the coils. The problem grows quickly when the air is humid, or the coils are dirty. How to fix it: Get a professional to inspect your refrigerant charge.
The most significant danger of frozen evaporator coils occurs if you keep running your AC unit. Then you may cause permanent damage to your entire air conditioning system.
Regardless of how AC coils freeze, the end result is usually the same: your AC system can't effectively cool your home. Plus, you'll probably run up your utility bill desperately trying to achieve a comfortable indoor climate.
Cold coils: If the temperature of the evaporator coils falls below 32 degrees, water vapor in the air surrounding the coils will begin to freeze when it comes into contact with the coils. At first, there may be only a thin film of ice or frost but over time, a large coating of ice can build up.
Try a Little Heat
As previously stated, simply shutting off the AC will not melt the ice fast enough. It can take more than a day before it's nice and toasty. You can speed up this process with some heat directed towards the ice.
You must be surprised to know this, but using a hairdryer can be the most accurate way to defrost your air conditioning unit. You can use a simple hairdryer or a blow dryer and run it after pointing towards the evaporator coils. However, you must ensure that you do not run the hairdryer at a higher temperature.
Without the proper airflow to flow over the evaporator coil, the temperature will quickly drop below the freezing point of water. Ice will now begin to accumulate on the inside evaporator coil. If you're running a heat pump in winter, this can also happen outside on the condenser coil.
Another thing that causes an air conditioner to freeze is low refrigerant or Freon. This causes a drop in pressure inside the evaporator coil, which then allows moisture in the air to accumulate and freeze on the coil. A leak is typically responsible for low refrigerant.
As always, turn the air conditioner off as soon as you notice freezing. Keep the fan on, though, so it will blow warm air over the frozen components. This will help thaw your system within a few hours in most cases. From there, the first step is to check your air filter and return vents.
The short answer is that whenever there's blocked airflow through any of the air conditioner's components, a portion of the AC will freeze. There are several things that could cause blocked airflow: dirty air filters, clogged condensate line, dirty coils, refrigerant leak, a faulty fan, among others.
The good news is that you absolutely can spray water on your air conditioner if it needs a cleaning, and nothing bad will happen. Spraying water on your AC's condenser also helps it run more efficiently. In fact, your condenser needs a regular spritzing in order to keep doing a good job.
Yes, you can hose down your ac unit. In fact, spraying water on your air conditioner to clear dirt and other debris, along with a regular/preventative maintenance plan can help keep your air conditioner unit running more efficiently.
Check the air flowing through the supply registers.
If it's warm or the air is stopped altogether, frozen coils could be the problem. Frozen AC coils can lead to a buildup of moisture, which could cause condensation or water leaks in your building.
As the indoor temp reaches 68 degrees, there is not enough heat in the air passing over the indoor cooling coil which causes it to get too cold and freeze. A faulty contactor in outside unit will cause freeze up because the outdoor unit keeps running when it should be off.
The lower limit
Even when the temperature outside isn't at heatwave levels, we recommend you don't lower the AC's setting below 68°F. This temperature is already more than cool enough for most people, and many will find it too cold.
The first thing to check is your air filters. Lack of air flow will cause the system to freeze up. If your filters are dirty and have not been changed for a long period of time, that may have caused the issue. Just replace the filters with clean ones.
Dirty Air Filter
If you don't replace or clean your air filter, it could become dirty or clogged and cause improper airflow. Ice is bound to form on the evaporator coil when air is not getting through. Changing your air filter will keep your air conditioning components from freezing.
What happens if you set your AC too low? Air conditioners are not designed to operate in or produce temperatures below 60 degrees. Truth be told, they're happiest around the 68 degree mark. Most thermostats simply won't allow you to choose a setting below this mark.