AC unit freezing up in summer

AC Unit Freezing Up In Summer

Irony. That may too kind of a word for it.
The hottest time of the year and the air conditioner is not working. Right when you need it the most. But the AC unit freezing up in summer is not unusual.

Why is the AC freezing up in hot weather? 

The AC needs two things to make sure it’s able to cool down your house properly. Good airflow and the proper level of refrigerant.
When the days get hotter, the thermostat tends to get adjusted to a lower setting which makes the AC work harder.

Ice forming on AC coils? 

Ice forming on the AC coils is a symptom of a unmaintained air conditioning unit that is working harder because of the temperature getting Hotter outside.

If you see ice forming on your air conditioner, it not only means that your air conditioner is not going to be able to do its job, they can also result and costly in repairs. So it is important not to let the problem linger.

What causes an AC unit to freeze up?

1.  Dirty filters

Number one on the list. Dirty filters.
When you have any kind of issue with your air conditioner, the first thing to check is if the air filters have been neglected and need changed.

A Dirty or clogged filter restricts the amount of air that is able to flow across the AC coils. When there is not enough hot air moving across the coils, the refrigerant is so cold, the condensation on them freezes.
Keeping the air filters changed at least every 2 to 3 months is the easiest way to keep your unit working properly.

2.Vent registers

Other restrictions in the air flow can result from closing supply and return vents. If the AC is freezing up, making sure all the vent registers are open and not being covered will help the air flow also.

3. Low Refrigerant

A unit that is low on refrigerant will cause the AC coils to freeze over to.

If cleaning the filters and opening the vents does not get the air conditioner functioning again then it could be a refrigerant leak.

A technician can tell you whether or not you need freon in your system.
But remember did the air conditioner is not made to have to be recharged.
Recharging the refrigerant may help you get through the year but you will probably need to do it again every year to you get the leak fixed.

What causes an AC unit to freeze upHow to tell if AC is Frozen?

How can you tell if the air conditioning coils are frozen over?

1.  The easiest thing is the turn off the air conditioner and let it run on “fan mode” for a while.
If you turn it on after a couple of hours and cool air comes out again. Bingo, you have discovered that your AC is Freezing.
2.  Check and see if there’s any water coming out of the drain line. A properly functioning AC will have a continuous drip from the drain line. If it’s frozen, it won’t drip.
3. You can visibly see ice on the outside of the unit. Check the insulated pipes running out of the AC also. If the AC is Frozen, you’ll likely see ice formed there to.

AC Frozen –  how long to defrost? 

How long you have to let your AC defrost depends on the the amount of ice that has formed on your coils.
45 minutes is a good spot to try your AC and see if it’s cooling again.
In the meantime, make sure your filters are clean and your registers are open and not blocked or your AC will probably freeze over again pretty fast.
Especially if not all the ice has thawed.

How to unfreeze AC unit fast 

1.  Fan mode
Set the thermostat to Fan On mode.
Letting the AC run on Fan will blow warm air across the coils and help the ice and refrigerant thaw out faster.

2.  Hair dryer

You can use a hair dryer to help it’s all out a little faster. You sure you completely turn off your unit at the breaker box first. If you need the ice gone quicker than letting it thaw out.
Using a hair dryer can help you fill it out a little faster. Be sure you don’t try to step it up to a torch or heat gun. You definitely don’t want to do any damage to your machine.

Can I pour hot water on frozen air conditioner?

3. Pouring hot or warm water over the ice coils outside is it perfectly good way to thaw out the coils faster.

But be sure to turn the AC off at the breaker box.
The water inside the garden hose is usually warmer in the summer to.
And gives you a good reason to clean and remove any debris from the outside of the unit while you’re at it.

AC unit freezing up at night 

When your AC is freezing up at night, it is most likely the fact that the temperature is getting to cool at night to keep warm moving across the AC coils.
Even in Summer, the days can be miserably hot while the night air puts a chill in your bones.
Turning the thermostat up at night should help keep the air warm enough to keep your AC from freezing at night.

Remember the AC filter is the place to look first. If it is clogged, the air will not move across the coils fast enough regardless of whether it’s day or night, summer or fall.

Wrap up

what causes an evaporator coil to freezewhat causes an evaporator coil to freeze?

The most common issue with the AC evaporator coils to freeze is poor air flow.
If the air filters have not been replaced recently, then that is more than likely the problem.
Another air restriction that can aid in the AC freezing over is closing the supply and return vents.
Make sure all the vents are open and that there’s nothing blocking them.

Low refrigerant is also a possibility when the AC is freezing over. Low refrigerant in an air conditioner is a sure indicator that you have a leak in the system.
Getting a licensed AC tech to find the leak, fix it, and recharge the unit is the best path to take.


Published by

Dennis Reed

Dennis Reed Owner and Author @