Car AC Evaporator Freezing Up – What To Do?

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The comfort in a car with a good air conditioner blowing cold air is unrivaled. But even after buying a car with a good AC, the AC can develop faults over time. One of the common issues is a frozen evaporator. We consulted with auto-technicians and according to their advice, here's the best way to deal with this problem. 

A frozen AC evaporator is usually due to the AC absorbing moisture, dirt, or other external factors into the evaporator. If the culprit is moisture, the best you can do to revive your AC is to extract the moisture safely. Then you can now proceed to any other necessary repairs. 

There is still a lot to learn about your car's AC evaporator, so stick around to learn what to do if you encounter this problem. 

Car ac evaporator maintenance check by a mechanic, Car AC Evaporator Freezing Up - What To Do?

Car AC Evaporator [Functions and Uses]

The car AC has several parts which include the unit, lines, o'rings, pipes, and one of the most important is the evaporator. Firstly, the evaporator's primary job is to absorb heat from the surrounding air. If you are in your car and you have the AC on, the evaporator, which has an affinity for heat, extracts hot air from the surroundings. 

Then, the evaporator works with the blower as a cooling unit to release cold air to the surrounding area. Even if the AC continues working without the evaporator working correctly, heat would not be absorbed, but cold air will be released in bits. 

The evaporator accommodates heat, hot air, and a bit of water vapor that would have caused inconvenience for the driver of the car and his team.  

hand driver man checking adjusting air from conditioning the cooling system with flow of cold air in car

What Causes Car AC Lines To Freeze? 

Whether in the hot summer or cold summer, the AC lines could be frozen. However, there are various reasons this would happen. The issue might not even be related to the weather. The AC lines are not expected to freeze during hot weather, so what could cause them to freeze suddenly? 

AC lines can freeze as a result of a faulty AC evaporator. As stated earlier, it is in charge of a lot of functions, and when it becomes too cold, the effect will be felt on the AC lines unit too. 

If the AC evaporator heat absorption mechanism is not working smoothly, the evaporator only produces frigid air or ice that would sediment on the lines. 

Meanwhile, here are other reasons your AC lines would be frozen:

  • Disabled blower fan 
  • Evaporator leak
  • Damaged refrigerants
  • Accumulation of dirt and moisture in the coil.
  • Damaged air ducts and so on.
  • Build-up of debris
  • Closed air vents

You would probably need the expertise of automobile experts to check your AC lines before they can determine what the main issue is. But these are the most common reasons for your AC line freezing. 

How Do I Know If My Evaporator Coil Is Frozen? 

External air-cooled condenser used in water cooler or refrigerator

An air conditioner in your car or home might not be working properly because of a frozen coil. If you are not sure of what to check for, here are the signs that you will notice once your evaporator coil is frozen:

  1. If the air coming out of the supply register is warm, your evaporator coil is frozen.
  2. Check the filters if they are dirty or clogged with dust.
  3. If the coils and the cooling fins are dirty or surrounded by dust, then the evaporator coil might be frozen. 
  4. Probably, there is ice on the evaporator itself. They are almost visible with the eyes. Although, you can unscrew it to check the evaporator if there is ice. 
  5. If the air conditioner register is blocked with dirt, the coil would be frozen too.
  6. A frozen evaporator coil will never work correctly with another part of the AC. So, the AC would not cool.
  7. If the condensate drain pan is overflowing, it is a vital sign that the evaporator coil is frozen. 
  8. Another sign is if they were ice at the outer part of the AC (maybe during summer).

After observing the above signs in your air conditioner, the best you can do is to allow it to thaw completely before turning it on again. Meanwhile, if you cannot decipher where the fault in your car's air conditioner is coming from, you can take it to an auto technician for a proper check-up. 

How Do You Stop An Evaporating Coil From Freezing? 

aluminum fin of cooling condenser coil air condition system

If you want to stop the evaporating coil of your AC from freezing, then there are a few preventive measures you need to take; they are as follows: 

Change The Air Filter Every Month

The air filter helps to filter the air passing through the AC. It does the same for the cool air leaving the evaporating coil too. 

If clean air is not coming through the air conditioner because the air filter is already cloggy or dirty, the evaporating coil or AC unit will freeze. Therefore, make sure that you clean your filter at least once a month.

Check The Air Vents

The air vents are another part of the air conditioner that harbors dirt and dust. It is better to get them checked regularly and perhaps clean them once in a while. 

Check The Refrigerants Level

The problem with your AC might not even be from the unclean surrounding air; the refrigerants might be contaminated or leaking. The number of refrigerants in the AC will reduce as the refrigerant leak. Once it gets too low, it might result in your evaporator coil becoming frozen. Hence, producing warm air. 

Increase The Fan Speed

Increasing the fan speed can blow dirt out of the air conditioner system. If the motors are working well and the fan itself is clean, the issue of evaporating coil freezing would be reduced. 

Check The Condensate Drain

The condensate drain is the passageway for water to leave the air conditioner.  Over time, any sediment settled from the water might cause the blockage of the condensate drain. So, it is best to keep the condensate drain very clean. 

How Do You Fix a Frozen Evaporator? 

If your evaporator coil is already frozen, you can also restore it. The main thing you need to do is switch off the air conditioner and thaw it. You can do this at home if you have the expertise.  This will help reduce the risk of causing any more damage to your air conditioner. 

You can follow the steps to be explained below if you still want to persist with fixing the air conditioner: 

  1. Turn off the air conditioner and disconnect all the electric cables. 
  2. Open the access door, which will lead to the evaporator. 
  3. Firstly, check if the evaporating coils are frozen already. If they are, do not use a hammer or your hand to remove the ice because it will affect the coil. However, you can use a soft brush to carefully scrub the ice. 
  4. Then make sure all dirt and dust is entirely removed. 
  5. Avoid over-pressurizing the coil or evaporator.
  6. Straighten the heat transfer fin if there are any defects.
  7. Make sure you cover the access door and screw back the covers. 

How Long Does It Take For an AC Coil To Thaw? 

It can take about two to 24 hours for the AC coil to completely unfreeze. However, this is dependent on the size of the AC coil, the AC, and the thawing process. 

Can I Use a Hair Dryer To Defrost My Car AC? 

Hand pressing the black blower

A hairdryer is one of the most efficient tools you can use to defrost the air conditioner in your car. Instead of using your hand or a soft brush to scrub the ice, you can use a hair dryer to remove all the ice. 

Remember to make sure that your hair dryer or a blow dryer is not at a very high temperature when using the hair dryer to defrost the coil.

Should I Pour Hot Water On a Frozen Car AC Unit? 

You can pour moderately warm water on a frozen car AC unit to thaw frozen coils. However, there are other ways to safely thaw a car AC unit, as explained in this article. 

Conclusion

Car ac evaporator maintenance check by a mechanic

A frozen car AC evaporator would affect the way your car AC functions as it would also affect the lines and coil. In this article, we have explained ways to safely get rid of ice in your car's air conditioner and even fix any issue regarding freezing for the air conditioner to work well. 

For more articles on car air conditioners, check out these related articles: 

How To Bleed Off an Overcharged Car AC

Why Does My Car Air Conditioner Only Work On High? 

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