Why Your HVAC is Freezing Up and How to Fix It

by | May 2, 2024 | HVAC System

Have you ever checked your HVAC system only to find it resembles a mini igloo? An air handler covered in ice is a clear sign of trouble, indicating your system is working inefficiently. Here’s a guide to understanding why your HVAC unit might be freezing up and what you can do about it before calling in a professional.

1. Check Your Air Filter

A common culprit for many HVAC issues is a dirty air filter. If the filter is clogged, it restricts airflow, forcing the system to work harder and potentially causing it to freeze. It’s a good practice to check your air filter monthly and replace it if it appears dirty. This simple step can prevent a multitude of problems.

2. Ensure Adequate Air Flow

Restricted airflow can also lead to a frozen unit. Make sure all your supply registers and return grilles are clean and free from obstruction. Even simple things like furniture or drapes blocking an air vent can cause significant issues with airflow, leading to freezing.

3. Adjust the Thermostat

Sometimes, setting the thermostat too low can cause your unit to run longer than necessary, leading to freezing. Try setting your thermostat to a moderate temperature to prevent overcooling and freezing.

Professional Checks Needed

If the basic DIY checks don’t resolve the freezing issue, here are some areas where a qualified HVAC technician will need to step in:

4. Inspect the Evaporator Coil

The evaporator coil absorbs heat from the air in your home, and if it’s dirty, it can’t perform efficiently. A professional can clean the coil to ensure it functions correctly.

5. Check Refrigerant Levels

Low refrigerant, often due to leaks, can cause the evaporator coil to freeze. Since handling refrigerant requires special training and certification, this is a job for a professional.

6. Examine the Blower Motor

The blower motor drives the fan that moves air across the evaporator coil. If this motor is malfunctioning or not running at the correct speed, it could be contributing to the problem. A technician can diagnose and repair issues with the blower motor.

7. Assess the Ductwork

Problems in the ductwork, like leaks, bends, or obstructions, can restrict airflow and lead to freezing. An HVAC professional can inspect your ductwork for any issues that need repair.


While some issues like changing a dirty air filter or adjusting the thermostat are easy fixes, other problems will require professional attention. Remember, never use an external heat source like a hair dryer to thaw ice on your HVAC unit; not only is it unsafe, but it can also damage your system. If your HVAC continues to freeze up despite your best efforts, it’s time to call in a certified technician to ensure your system runs efficiently and safely.

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