Why Is My AC Freezing Up? Causes and Solutions

Why AC Units Freeze

It seems counterintuitive - how can something freeze when it's hot outside? Here's what happens:

When airflow is restricted or refrigerant is low, the evaporator coil gets too cold. Moisture in the air condenses and freezes on the coil, eventually building up into ice.

Common Causes

1. Dirty Air Filter (Most Common)

A clogged filter restricts airflow, causing the coil to get too cold.

Fix: Replace the filter and let the system thaw.

2. Low Refrigerant

A leak causes pressure changes that drop coil temperature.

Fix: Requires professional repair - refrigerant handling requires certification.

3. Blocked Vents

Closed or blocked vents reduce airflow through the system.

Fix: Open all vents and remove obstructions.

4. Dirty Evaporator Coil

Dirt insulates the coil and affects heat transfer.

Fix: Professional cleaning recommended.

5. Fan Problems

A faulty blower motor reduces airflow.

Fix: Professional diagnosis and repair.

What To Do Right Now

• Turn off the AC - Set to OFF or fan-only
• Let it thaw - This takes 2-4 hours
• Check the filter - Replace if dirty
• Check vents - Make sure all are open
• Try again - If it freezes again, call a pro

When It's Serious

Call immediately if:

• You hear hissing sounds (refrigerant leak)
• Ice builds up quickly after restart
• Problem happens repeatedly