what will cause an evaporator to freeze up

There is no worse fear on a hot summer twenty-four hours than turning on your air conditioner just to discover out it isn't working. To make matters worse, yous discover that ice has congenital up on your HVAC system when you go to investigate.

Frozen air conditioners tin be worrisome, and the repairs tin be costly, specially if y'all can't diagnose why the system is freezing. There are several reasons your AC tin freeze up, and this article volition cover them all. We will help you observe out why your Air conditioning is freezing and what you lot tin can do near it.

Understanding How an AC Works

Before yous can diagnose what is causing AC freeze up, y'all should take a bones understanding of how the organisation works. Knowing how everything goes together volition aid you diagnose where the trouble is and which components or parts are causing it.

A central air conditioner has two main components, the evaporator, and condenser. The refrigerant lines run between the 2, which is where the heat is transferred from the air inside to the air outside.

The condensing unit takes the hot refrigerant gas and moves air over the coils, which remove the heat from the gas. The cooler gas is then sent through the compressor. Here it is compressed rapidly into a high-pressure liquid, causing it to rut up.

Once the hot liquid refrigerant leaves the compressor, it is sent through an expansion valve and filter drier. This releases nigh of the heat and begins the expansion process, where the liquid turns into a gas.

This semi-gas then enters the evaporator, where information technology forms into a cold gas that removes heat from the inside air as it travels through the evaporator coils. This causes the air to become quite cold and is sent by the blower through the ducting and out into the rooms of your habitation.

The gas in the coils heats up and is returned to the condenser, where the wheel repeats. What is virtually crucial to understand, though, is that the evaporator and condensing units are calibrated specifically for your installation, and the refrigerant is calculated by temperature and weight.

The evaporator will not heat more refrigerant gas than the condenser can handle, and the compressor will not send more liquid refrigerant than the evaporator can handle. If this process is always disrupted, freezing can occur.

Signs That Your Air Conditioner Is Freezing Upward

There are many signs and causes that your AC may be freezing upwardly. Here nosotros will cover these reasons and signs that your organisation is in danger of freezing upward.

• Really freezing up.
  It is possible to see the evidence before yous notice annihilation. Ice building upwards on the depression-pressure line leading to the condensing unit is the first sign. Information technology will then move through the condenser and compressor.
• Lowered airflow.
  When the organization is running, yous may observe no air (or depression volume) coming from the vents. This can happen suddenly, which is a clear sign of freezing.
• Warm air from vents.
  If the evaporator is frozen, at that place can still be solid airflow, but the air volition be warm. If your domicile is non cooling (or even getting hotter), freezing is a potential suspect.
• System running constantly.
  If your AC never seems to shut off or turns dorsum on right abroad, running in a near-constant land, it may be freezing up.

Reasons Why Air Conditioners Freeze & How to Fix Them

Now that yous know the signs to await for, let'southward have a look at the reasons those signs of freezing appear. There are quite a few, so proper diagnosis may non happen right abroad.

Low Refrigerant Levels

The only caption for depression refrigerant is a leak. As a sealed system, there is no other way for refrigerant to leave the refrigerant lines. Nevertheless, a bad valve, pinhole in the refrigerant lines, or a faulty component can cause the refrigerant to leak out slowly.

When it gets as well low, the refrigerant cannot shrink enough or move through the system fast enough to maintain the rut substitution. This causes the depression line and the coils to go colder and colder until water ice forms. As the ice continues to spread, the system gets slower until it shuts downwards to freeze solid.

To fix this result and forbid ice from forming again, you will demand to locate the leak and repair information technology. This may take a trained HVAC professional using leak detection equipment and repair methods.

Drainage Bug

Another aspect of freezing systems is the drainage lines from the drain pan. While this isn't the almost mutual reason for freezing, it can exist a factor. If the drain pan becomes clogged, the cold water dripping from the evaporator coils volition collect in the drain pan and cause the heat substitution in the evaporator to slow.

If it goes on long enough, the cold evaporator coils will commencement to freeze and, over time, can encase the entire evaporator system. This is also one of the hardest to diagnose since the organization will all the same run correctly for a while, and the ice can melt when the organisation is off, removing whatsoever trace of a problem.

To fix this result, you need to unclog the bleed, clean the drain pan and ensure proper drainage through the organisation. The use of drain pan tablets can help prevent time to come clogs.

Faulty Fan

Besides low refrigerant, the other major cause for frozen lines is depression airflow. The trouble with this diagnosis is that there are many reasons for low airflow in a system. One of those reasons, though, is a faulty blower fan.

If the fan in the evaporator unit is not running correctly, is intermittent, or has stopped birthday, then there isn't any warm air being pulled over the evaporator coils. This causes the heat commutation in the evaporator to slow or even stop, and the cold refrigerant in the coils will cause ice to form. This volition even further diminish the airflow, compounding the problem.

If the fan is faulty, replacing the fan motor is your simply option, unless at that place is a secondary cause of the error, such as loose or bad wiring or a bad run capacitor. Information technology may accept the inspection from an HVAC technician to properly diagnose.

Faulty Thermostats

Some other uncommon merely easily missed cause is a faulty thermostat. The thermostat tin can brusk out in the run position, forcing the arrangement to continue running, even when the condensing unit has shut off. If the evaporator unit is nonetheless trying to cool the air and the compressor is not running, ice can form in the evaporator.

There are many reasons a thermostat tin can short or fault, but dust and low batteries (if equipped) are the most common. Replacement of a thermostat is a fairly simple DIY projection, and you lot tin also take the opportunity to upgrade to a smart thermostat.

Learn near the differences betwixt analog Vs digital thermostats here.

Low Outdoor Temperature

Running the air conditioner when the ambient outdoor temperature is too low will also bear upon the rut substitution. If the refrigerant is cooled too much at the compressor, it won't pressurize enough. A lower pressure refrigerant running through the high pressure level line can too cause freezing.

When this happens, you volition generally see the high line become frosty long earlier the low line starts to ice over. However, once the freezing reaches the evaporator, information technology simply takes a few run cycles to reach the depression line and compressor itself.

The but solution for this issue is to non run the air conditioner when the outside temperature is as well depression.

Grit Blocking The Coils

Grit and droppings build up on the evaporator and condenser coils, and they must exist cleaned regularly. Even so, even betwixt cleanings, at that place can be enough aggregating to cake proper airflow.

If the coils in either place become blocked enough and the airflow is impeded, ice volition begin to form and spread throughout the system. Using coil cleaners, fin combs, and removing debris from the evaporator or condenser coils will commonly exist enough to ready this freezing issue.

Lack of Airflow

Just every bit blocked coils can impede airflow and disrupt circulation, so can a dirty or clogged air filter. This is the nearly straightforward trouble to solve and diagnose. But remove the air filter and turn the system dorsum on (but for a few minutes). If air flows properly and blows cold, supersede the filter with a new i.

Other airflow issues can exist acquired by a number of other issues y'all may not run across. Damaged or complanate ducting, for example, or a faulty run capacitor not providing plenty voltage to run the fan at a high enough speed. If you have make clean coils and have replaced the air filter, and are still experiencing depression airflow, y'all should call an HVAC tech in to diagnose the issue.

How to Set Frozen AC Components

When you detect ice on the lines, pipes or components, the get-go thing yous need to do is shut the system off. You lot will need to wait until the ice is completely melted and removed before attempting whatever repairs or replacements.

You likewise need to follow all safety and gamble warnings, protect yourself from electric shocks, and never piece of work on the organization with breakers, thermostats, and the system yet powered on.

Air Conditioner Line Frozen

The air conditioner pipes, or copper lines, are unremarkably (though non always) the first to freeze over. The low pressure line is already colder to begin with, and any drop in the flow rate of the refrigerant, pressure on the line, or desperate temperature change tin can crusade them to freeze. You will notice this happening on the larger line leading to the condenser unit outside.

When this happens, the beginning matter you need to exercise is shut the system off. If the line is only frosted, y'all should bank check the easiest components get-go. Supplant the air filter and inspect the thermostat for harm or shorting.

If the airflow is sufficient, it is most likely a leak in the refrigerant pipes, and you volition need to locate the leak and repair it. An HVAC technician should be chosen to locate and perform the repairs on the leak. Once the leak is fixed, the technician can too refill the refrigerant to the proper amounts to forbid future freezing.

Air Conditioner Coils Frozen Over

When the condenser coils (exterior unit) are frozen over, information technology tin can be because of a refrigerant leak, only the nearly common culprit is a faulty fan motor. Yous can check this quickly by leaving the system running and checking if the fan is spinning (visual check only).

If the condenser fan is not moving, the coils can freeze. This will also cause the compressor to overheat, which may trigger the overheat protection switch, shutting the compressor off. With the compressor off, the refrigerant doesn't cycle, and ice begins to course.

A bad fan motor will need to be replaced. However, you need to ensure that the motor is the aforementioned size, rotation, wattage and output as the original motor. Replacing with a smaller motor or larger motor can outcome in overheating or icing just as easily.

Air Conditioner Frozen Inside Scroll

If y'all notice a lack of airflow from the vents in your home, information technology is most likely a frozen coil in the evaporator. Opening the evaporator access panel will let you to see the evaporator coils, and yous will be able to tell right away if they are frozen or merely dingy.

If they are frozen, yous will demand to defrost them and so y'all can detect the underlying trouble. Leaving the arrangement on in fan-only mode will aid defrost faster while existence less likely to overflow the drain pan.

Once defrosted, you can run the arrangement with the access panel off to encounter if the blower fan is moving. If it is, the trouble is nigh likely a leak in the refrigerant lines, which volition need to be inspected and located by an HVAC technician. If it is not moving, you will demand to replace the blower motor fan or hire a technician to exercise information technology for you.

Air Conditioner Indoor Unit Frozen

If the evaporator itself is frozen and not merely the coils, the most likely crusade is a faulty blower motor. However, blocked airflow is too highly probably and easier to diagnose. The showtime footstep is to remove the ice. Once the organization is defrosted, you can better diagnose the outcome.

Turning the Air conditioning back on afterwards the ice has melted will tell yous pretty quickly if it is an airflow issue or a leak. When running, cheque the air force per unit area coming from the vents. If there isn't whatever, yous can open the evaporator access panel to come across if the blower fan is moving.

If information technology is, the problem is near likely a clogged filter or a collapsed duct. The filter you can replace yourself; all the same, it is ameliorate to have a technician diagnose and repair complanate ducting or a leaking refrigerant line.

RV Air Conditioner Freezing Upward

If yous experience ice in your RV's air conditioner, the aforementioned reasons tin use. Still, because the system is more compact, closer, and exposed to the elements, it is nearly probable a muddy external unit.

The offset thing to check, though, are the easy things. Ensure that the filter is new, or at least non clogged or dirty. Double-check that the frazzle vents are also cleaned as debris and dust tin can cake airflow exiting the arrangement.

Finally, before climbing on the roof, check that the thermostat is in working order and everything comes on when the thermostat is used. If all of that fails, you should remove the shell of the top mount unit and inspect the coils for dirt and droppings build-up blocking airflow. Make clean the system according to the manufacturer's specifications and try the system once again.

If it all the same continues to freeze up, you will need to have it inspected past an RV HVAC technician for refrigerant leaks and repairs.

Tips on How to Keep Air Conditioners From Freezing Upwards

Of grade, the best class of activeness is preventative. If you can go on your system from freezing upwards in the start identify, you lot won't take to worry almost dealing with ice in your air conditioner at all.

There are several things you can (and should) do to help preclude ice build-upward in the first place.

• Change filters.
  Your air filter isn't designed to last forever. When you buy a filter, it will state the replacement schedule on the packaging. Most central air filters are designed for replacement every xxx, 60, or ninety days. Make sure you supervene upon them on time to proceed airflow moving.
• Annual inspections.
  Calling an HVAC technician at the offset of each flavour is an inexpensive way to maintain your system. Most inspections terminal virtually two hours and will identify any problems or issues that you may have before you try to run the AC for the summertime. If any issues are identified during the inspection, scheduling repairs is besides simple and cheaper than waiting for the problem to get worse.
• Cleaning and maintenance.
  Every vi months, you should make clean the condensing unit outside, including the coils, fans, and compressor. You should too inspect and make clean the evaporator coils as needed. While this can exist a wearisome process, the few hours it takes to clean your organization is much cheaper than repairing costly components and paying labor charges for something that could have been prevented in the get-go place.
• Timely repairs.
  If a component such as a fan motor, filter, or capacitor does start to go bad, replacing it immediately instead of waiting for information technology to go worse is always a better choice. The longer you get trying to use a organisation not working at 100%, the more than chance you have of wearing out other parts prematurely.

People Also Ask (FAQ)

Tin can I pour hot water on frozen air conditioner?

Depending on where the water ice has accumulated, you can pour water on the AC. this unremarkably only pertains to the outside unit (condenser) if the AC lines and compressor are frozen. If the water ice is in the evaporator unit of measurement inside, using h2o to thaw may result in an overflowing drain pan, which can crusade a bigger mess. You tin can use tap water or running h2o from a hose, likewise; you don't need hot water to cook the ice.

What causes an evaporator coil to freeze?

At that place are a number of reasons evaporator coils will freeze. Low refrigerant and improper airflow are the two almost likely causes. However, intermittent fans, low outdoor temperatures, and a arrangement that won't shut off for electrical reasons can besides cause freezing.

What are the symptoms of a dingy condenser curlicue?

When a condenser coil is dirty, airflow is blocked. This results in the cooling of the refrigerant to stop. Pushing hot gas through the compressor prevents proper pressurization and makes the organization run much colder than it should. Eventually, the condensing unit'southward lack of rut exchange will cause the compressor and high pressure lines to freeze, which can speedily reach the evaporator.

How long does it accept for AC to unfreeze?

The time it takes to unfreeze an Air-conditioning system will depend on the extent of the freezing and where information technology originates. Unfortunately, nosotros don't have visible access to the evaporator in nigh cases, and if the freezing starts in the evaporator or its coils, you may not notice it until information technology gets bad plenty to get-go freezing the refrigerant lines leading to the condenser unit exterior. In most cases, with ambient room temperature, yous can expect a full defrost in a couple of hours or less. You can speed upward the process by turning the organization to fan only manner, which will motility warm air from the home over the coils. Otherwise, you volition need to await.

Should in that location exist ice on AC coils?

There should never be ice anywhere on your AC system. The refrigerant running through the condenser is hot and should never be at a temperature that results in freezing. In the evaporator, the coils may show signs of slight frosting but shouldn't ice over at all. If you discover ice on either set of coils, there is an underlying problem that should be located and repaired.

How do I add Freon to my AC unit without an HVAC professional?

To handle, add, remove or dispose of refrigerant (sometimes mistakenly referred to as Freon), you must concur an EPA 608 certification. Unless you lot piece of work in the HVAC manufacture, you probably do not accept this certification. If your air conditioner needs to be refilled with refrigerant, you will need to contact a licensed professional person. Still, low refrigerant means in that location is a leak in the system somewhere, which should be located and repaired before refilling the refrigerant, or your system will run low and freeze up again.

Exercise I need a professional to help unfreeze my Ac unit?

You do non need a professional person to unfreeze your AC. Simply turning the system off and waiting for the water ice to melt is all it takes. However, when at that place is ice build-upwards on the coils, lines, or compressor, it is an indication that something more serious is wrong. You may demand an HVAC professional to locate, diagnose and repair the underlying problem.

Conclusion

A frozen air conditioner is never a good thing. When working properly, an air conditioner should cool the air enough to lower the indoor temperature but not become so common cold information technology starts to class ice.

This article explained why a system might begin to ice over and showed you how to place, repair or fix the underlying issues causing the freezing. Hopefully, you have a better idea of how to maintain your HVAC system to prevent freezing in the outset place and what to do if it does happen to y'all.

Last Updated on July 16, 2021

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My name is Josh and I am obsessed with the HVAC industry. I created this website to assist HVAC techs of all levels get the best out of their heating & cooling systems. I have spent thousands of hours studying air conditioners, heaters and dwelling house air products so y'all can learn & buy with confidence. Learn more than nearly the team here.

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