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HVAC Unit is Frozen in Winter?

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During these cold days and nights, having your HVAC stop working could become a nightmare.  A small problem can turn into a costly repair if you don’t keep your HVAC working at its best. Scheduling your unit for routine maintenance by a licensed technician is one of the best ways to prevent future problems during any season.  Your HVAC is a very important and expensive part of your home.  Get the most from it by making sure it is operating at its best year-round. When you are facing a frozen HVAC unit, most of the time it could have been prevented with a routine check.

What You May Ask When Dealing With a Frozen Unit

What does it mean to have a frozen unit?

If you have a frozen unit, it means that your outside unit is freezing over and not thawing out. It is normal for your heat pump system to freeze over periodically when in Heat Mode. The unit has a built in control that will put it in “defrost mode” every 30, 60 or 90 minutes. Defrost mode is virtually “Cool mode.” It blows hot air outside and cool inside. This makes up for the cool air it is blowing inside the system to run the electric heat strips to negate the cool air. 

What can I expect if this happens?

This can cause multiple issues and also indicates there is already an issue. It could be from a low refrigerant amount, or other issues with the refrigeration system. It could also be a failed defrost control. 
In any event, if your hvac unit freezes and never thaws out, something is broke. A more sever repair will happen if it is not addressed asap. It will cause high utilities and of course, affect your comfort in the home. 

What causes a heat pump to freeze?

Most heat pumps have automatic controls.  This allows for the machine to self-maintain but putting itself into defrost mode, preventing ice buildup.  Restricting the airflow around the unit can cause ice to build up too fast, though. Have your filters and duct work checked for any debris.  Also, make sure there isn’t any build up of leaves or snow around your unit that could decrease the air flow.

Would a dirty filter cause unit to freeze?

A dirty air filter limits airflow. Lack of airflow around an HVAC unit can cause it to freeze. This is because the humidity would rise in this area and cause more precipitation to form on the coils. An air filter that is too restrictive can also cause this.

Why is my HVAC unit frozen in the winter?

Ultimately it is excess moisture that will allow your unit to freeze. One reason this could happen is in Alabama we have many warm days in winter. The excess moisture in the air will build up on the unit. When the temperature drops and the moisture freezes, it makes it difficult for your unit to perform properly.

How do you know if your AC froze up?

First, turn off the system. Second, turn on the blower. This helps to thaw the evaporator coils. If you feel warm air coming out, then your unit may be frozen.

It Is Frozen. Now What?

How do you unfreeze an air conditioner?

First know that this will take a few hours. Switch off your thermostat and turn on your fan. It can defrost itself.

Can you pour hot water on a frozen AC unit?

We do not suggest that you do this. No hot water, no hose water, and no hair dryer. You also don’t want to try to break the ice with a sharp object. These quick fixes can damage your unit. 

See Also: Should I Cover My Heat Pump in the Winter?

If you have tried these methods but are still sitting in a freezing home, it is time to contact a professional. Make sure your technician is certified and licensed. Having a regular maintenance person who already knows your unit and any previous problems or maintenance done to it can help speed up the process. First because you may have an easier time getting an appointment. Second, they will already know you and your unit and can assess the situation better.

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