Your AC is freezing up or forming ice on the lines — here’s what’s causing it.
When ice forms on your AC’s refrigerant lines, evaporator coil, or outdoor unit, the system can’t transfer heat properly. The result: warm air from the vents, reduced airflow, and eventually a complete shutdown. Below we walk through the most common causes from most to least likely.
Common Causes
❄️ Dirty Air Filter MOST COMMON
A clogged filter restricts airflow across the evaporator coil. Without enough warm air passing over it, the coil temperature drops below freezing and ice starts forming. Pull your filter out and hold it to a light — if you can’t see through it, that’s your problem. This is the #1 cause of AC freeze-ups and costs nothing to fix.
🌀 Failing Blower Motor
The indoor blower motor pushes air across the evaporator coil. If the motor is slowing down, running intermittently, or has failed completely, there’s not enough airflow to keep the coil above freezing. Listen at the indoor unit — if the blower sounds weak, makes grinding noises, or isn’t running at all, the motor likely needs replacement.
⚡ Bad Blower Capacitor
The blower motor’s run capacitor provides the electrical boost to keep it spinning at full speed. A weak or failed capacitor means the blower runs slow or won’t start at all — same result as a bad motor: not enough airflow. Capacitors are cheap and easy to test. Bring yours in and we’ll bench-test it for free.
🚨 Low Refrigerant (Leak)
When the system is low on refrigerant due to a leak, the pressure drops and the evaporator coil gets too cold. You’ll see ice on the refrigerant lines going to the outdoor unit and possibly on the coil itself. Low refrigerant requires a licensed technician to find the leak and recharge the system — this isn’t a DIY fix. But you can rule out the other causes first before calling a pro.
🧹 Dirty Evaporator Coil
Over time, dust and debris build up on the evaporator coil, insulating it from the airflow. Even with a clean filter and working blower, a dirty coil can’t absorb enough heat and starts freezing. Cleaning the coil requires accessing the indoor unit’s coil compartment. You can try foaming coil cleaner, or bring your old filter in and we’ll help you figure out if the coil is the issue.
✅ What To Do When Your AC Is Frozen
Step 1: Turn the AC to OFF or FAN ONLY and let the ice melt completely (this can take 1–4 hours).
Step 2: Check and replace the air filter.
Step 3: Once thawed, turn the AC back on and monitor.
Step 4: If it freezes again, check the blower motor and capacitor. If those are fine, you likely have a refrigerant leak — call a tech.
Quick Diagnostic Checklist
Before you replace parts, check these:
☑️ Air filter clean? (Hold to light — should see through it)
☑️ All supply vents open and unblocked?
☑️ Blower fan running at the indoor unit?
☑️ Return air grille clean and not blocked?
☑️ Ice on the refrigerant lines outside? (Points to low refrigerant)
⚠️ Safety Note
Never chip or scrape ice off the coil or refrigerant lines — you can damage the coil and create a refrigerant leak. Always let it melt naturally with the system off. If you’re not comfortable working with electrical parts, bring your old part to our store and we’ll help you find the right replacement.
Need the Right Part?
Bring your old part to our Dallas store — we’ll test it for free and find the right replacement.
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Address: 10226 Plano Rd #104, Dallas, TX 75238
Phone: (214) 340-9421