Five reasons why your AC unit could be freezing up

Another very popular air conditioning repair phone call our company’s service department receives is the “My air conditioner is freezing up” or the “My air conditioner is a block of ice, help!” phone call. I put together a post with the five most popular reasons why an air conditioning unit would freeze up. Once again I am going to Frozen AC Coilemphasize that most people don’t realize that 80% of the time, most issues can have either been prevented or resolved through performing routine preventive maintenance on the HVAC unit. Below you will read the top five most common reasons why your air conditioning unit would freeze.

First, I would look at both the condensing unit, and the air handler. The condensing unit (outdoor unit) and the air handler (indoor unit) should both be running the same time. If the condensing unit is running but the indoor blow isn’t then you already found the bulk of the problem. The air handler motor could be stuck due to ice buildup. Shut the unit off and wait until the ice melts. Once the ice is totally melted, we can have some fun and start the trouble shooting process. Turn the unit on, and lets check out the below reasons.

Reason #1

The first reason why your air conditioning unit is freezing is because the evaporator fan motor is either bad or not running. Just because the evaporator motor isn’t running, doesn’t necessarily mean that the motor is bad, however I would suggest hiring an air conditioning company that can further diagnose why your evaporator fan motor is not running.

Reason #2

The second reason why your air conditioning unit is freezing is because of a dirty air filter. You would be surprised how many calls we go to and see that the AC unit froze up just because the customer never changed the filter. The reason why the unit freezes up is because the dirt in the air filter is restricting the cold air from passing through. I will discuss the importance of changing air filters in a future blog so stay tuned.

Reason #3

The third reason why your HVAC unit could be freezing is because of a dirty evaporator coil. Most of the time if someone neglects the air conditioning unit and fails to change the filter, the dirt ends up being sucked up by the evaporator coil. Just like when the filter is not changed, so too when the coils are dirty it restricts air flow from passing through the coil which then builds up ice.

Reason #4

The fourth reason why your HVAC unit could be freezing up is because of a low refrigerant charge. When you have a low refrigerant charge, it freezes up the pipes. The only way one can have a low refrigerant charge is if there is a refrigerant leak in the system. Refrigerant leaks can be very difficult to pinpoint. I would suggest hiring an air conditioning repair company and have them find and repair your refrigerant leak.

Reason #5

The fifth reason, and don’t think that this doesn’t happen because we have seen it plenty of times. People tend to turn the room with the air conditioning unit in it a storage room. Without realizing they block the return with boxes and it once again restricts airflow. The room with the air conditioning unit in it should stay clean.

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