How Do You Fix A Frozen AC Line?
Written By: Alexis Bennett
Edited by: Andrew Dunn
Looking for information on how to fix a frozen AC line?
Great, you are in the right place. In this guide you will learn:
- What is causing my AC line to freeze?
- Can I fix the problem on my own?
- What can I do to prevent a frozen AC line in the future?
- … and answers to all your questions about frozen AC lines.
Homeowners living through tough, hot summers often experience AC breakdowns. When you have a frozen air conditioner line and the AC stops working, you are stuck in the hot, humid (depending on where you live) summer weather. No thanks!
So if you find yourself with a frozen AC line, what are your options? Can you take care of a frozen AC on your own? That would be great. The good news is that many times, you can take care of it on your own by trying a few simple solutions.
What causes frozen AC lines, what are the solutions, and what happens if they don’t work? Let’s find out.
What's In This Guide?
What Causes a Frozen AC Line?
A lot can go wrong with central or room air conditioners. Here are just a few of the more common causes of a frozen AC line and other air conditioner failures.
- Refrigerant leaks from evaporator coils
- Accumulation of dirt over the coils
- Blocked AC vents
- Clogged air filters
- Blower fan failure
- Collapsed air ducts
- Low refrigerant levels
Before running out and tearing open your AC unit, you should figure out: which of these challenges can you take on yourself, and what should you leave to a pro? Great questions! Let’s break it down to DIY solutions and when to call in the AC cavalry.
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Fixing a Frozen AC Line Yourself?
Who better than Richard from Ask This Old House to troubleshoot your frozen AC?
Here are a few things to try when you find your AC line has a build-up of ice that is causing the unit to stop working properly.
- Switch from AC to fan – Give your air conditioning unit a chance to let that line unfreeze while you use just the fan. The solution really can be as simple as that. Wait to switch back to AC for at least 3 hours. If the air conditioner continues to freeze up, there are a few other things to try before you call the AC repair specialist.
- Check the vents – Sometimes supply or return vents get blocked up with dust or lint. Also, make sure supply vents remain open at all times. A closed supply vent means airflow is not getting through to the air conditioner, which can be the start of a freeze up and even more serious problems. Check rooms that are little used and may have vents closed, so supply and return can function at full capacity. This will ensure that evaporator coils are getting the warm airflow they need to do their job.
- Check the filter – You might not think a dirty air filter is a big deal, but they can really reduce the flow of air through your HVAC system, leading to frozen AC lines. Changing air filters is not that hard, so checking them can be a fairly simple step in fixing a frozen line.
What if DIY Doesn’t Fix My Frozen AC Line?
Ok, so you’ve checked the vents, the filters, and have run the fan. When you’ve done all the troubleshooting you can on your own, an AC repair might require a professional look.
What will the pros find that you didn’t discover on your own? Problems that an AC professional can find, diagnose, and fix might include any of the following.

Blower Motor
Does the fan sound different than it used to? Do you hear the fan running at all? It could be that the blower motor is not working properly, preventing the fan from drawing warm air in, and causing the lines to freeze up. Your HVAC service pro can fix or replace the blower fan and get your AC in good working order.
Refrigerant Leak
The problem might be due to a refrigerant line leak. Low levels of refrigerant can cause pressure to build up and inside the lines, and ice to accumulate on the lines. If you hear sounds like hissing or bubbling near the frozen line, a leak could be the problem. Your HVAC technician can check for leaks and fix them so cool air can flow and ice buildup can stop.
Problem with Ductwork
An HVAC professional can also check for tears or cracks at ductwork connection points, or even collapsed ductwork. Again, it’s all about airflow, and if ducts are damaged, the air is not flowing as it should, and one result of that can be frozen AC lines.
Whatever the problem, a licensed AC technician can examine your HVAC system, locate the problem, and correct it in time so bigger problems than a frozen line do not occur.
How Can I Avoid Frozen AC Lines?
Once you’ve fixed the problem, how can you avoid it in the future? A good maintenance plan can help with this. In addition to making sure filters are changed regularly, you’ll want to check on a few other areas regularly. This would include the air conditioner’s evaporator coil. These can and will collect dust over time, so cleaning a dirty evaporator coil yearly for an inside unit should be sufficient. Check outside units more frequently, as exposure to dust and dirt is a constant in that situation.
Coil fins can also get bent and cause airflow to be reduced. You can find a tool called a fin comb that will straighten out the fins and ensure better airflow.
You can do these yourself, or for more comprehensive maintenance and service, have a trained HVAC professional perform a service check and cleaning annually or at least every other year on your HVAC system.
Final Thoughts on Fixing a Frozen AC Line
You don’t want to go through a summer without your air conditioner running at full capacity. Now, if you find a frozen AC line, you have a plan of action. A frozen AC line could indicate a small problem that can be fixed with the right know-how. But it could also indicate a larger problem that should be left to the pros.
Knowing what to look for can make all the difference in getting your AC back up and running as quickly as possible.