Can I Turn on Heat to Defrost AC? Knowing Your Facts Straight

Homeowners often ask ‘Can I turn on heat to defrost AC?’ when they find out that their AC is frozen, and yet, they want to use the air conditioner. In general, a frozen AC isn’t an odd thing. You just need to unfreeze it.

However, you shouldn’t turn on the AC unit when it’s frozen because it will likely hurt the compressor. You don’t want to deal with compressor replacement, which would be the priciest repair job for the AC.

Read also: 3 Causes of Outside Air Conditioner Unit Frozen

How to Defrost AC Unit Fast

You should know that when you are dealing with a frozen AC, there is a big chance that the indoor evaporator coils are covered with ice. That’s the only part that you need to unfreeze. These (indoor) evaporator coils are cold coils, which means that they would freeze when there is not enough airflow or too cold. As a result, your AC unit is frozen.

can i turn on heat to defrost ac

In most cases, the unit should be able to unfreeze itself naturally. But then again, we are talking about the fast way to defrost the AC unit. If you are patient enough and willing to wait, the unit should be able to defrost itself. But if the room temperature is pretty low, the ice may not melt or it will take forever for the ice to melt. That’s why you need the proper heat to melt the ice.

Ensure that the condensate drain and drain pan are clear to prevent water damage as the ice melts. This is especially important if you have dirty air filters or a clogged air filter, which can restrict airflow and cause freezing.

Can I Turn on Heat to Defrost AC?

As it was mentioned before, you need heat if you want to defrost the AC unit fast. One way to do it is to use the fan-only mode or turn the heat on within the mini (split) heat pumps. You basically want to shut the refrigerant flow off and only make the indoor fan run. The warm airflow should be able to melt the indoor coils’ ice within 30 minutes to 2 hours.

This is called optional heating. You see, the airflow would reach the indoor evaporator coils naturally without the fan at around 10 CFM (or less). When you turn the fan on, you will increase the airflow to thaw the AC unit with 500 CFM or more.

These are some of the basic steps:

  • You need to leave the AC off (or the cooling mode off). You don’t need the refrigerant to flow. You simply want to turn the (indoor) fan motor on, which will spin that fan
  • Switch the (AC) fan setting to On from Auto. You need to know that when the setting is Auto, the indoor AC fan won’t be running when frozen. When you switch it to On, the fan makes the warm air flow over the (frozen) coils.
  • The brownish ice (located on the coils) would melt. You should be able to see that the whole thing defrosts within an hour.

Read also: Common Causes for Air Conditioner Fans Not Spinning

Keep in mind that the melted ice turns into water, which should be drained. After the ice is gone, wait for around 30 minutes for the water to be properly drained, so you can turn on the AC again.

How to Defrost Outside AC Unit

If you opt to use a hairdryer, be mindful of the dirty evaporator coil and clogged condensation drains, which can exacerbate the issue. Regular air conditioning services can prevent these problems.

You can always use the hairdryer with the right heat setting. First, you don’t want to use the ‘High’ setting at a very close distance. Just use ‘Low’ with 10 inches apart (at least).

But if you choose this method, you need to explore the coils, meaning that unscrewing the handler cover and removing the access panel would be required. This method only takes at least 10 minutes up to 20 minutes.


Remember, an AC unit that has to work harder due to issues like a refrigerant leak or poor maintenance can overheat and shut off. Allowing the unit to rest for 24 hours after defrosting can help it blow warm air more efficiently when you switch back to heating mode.

In the end, if you are careful, you should be able to defrost your AC without drama or hesitation with the above methods.

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AirconMag is an experienced author and Air Conditioner expert. With years of practical experience in the field authored several informative articles on various aspects of AC unit, including installation, maintenance, and repair