Quick Answer
Okay, so here's the quick version. Your AC's turned into a block of ice because it can’t breathe. Nine times out of ten, it’s a filthy air filter blocking airflow. First thing you do is TURN THE AC OFF at the thermostat, but switch the FAN to ON. This will thaw the ice safely. Don't you dare go chipping at it. While it's thawing, go check your filter. If it looks like a fuzzy gray carpet, replace it. That might be your only problem. If it freezes up again after that, you're likely low on refrigerant, and that means you've got a leak. That's a pro call, period.
Common Symptoms
Possible Causes
Step-by-Step Diagnosis
Step 1
Turn the AC system from COOL to OFF at the thermostat.
Step 2
Switch the fan setting from AUTO to ON to circulate air and melt the ice.
Step 3
Inspect the air filter for dirt and replace it if it's clogged.
Step 4
Check all supply and return vents in the house to ensure they are open and unobstructed.
Step 5
Wait for the ice to melt completely before turning the AC back to COOL.
Step 6
If the coil refreezes after these steps, it indicates a more serious problem like a refrigerant leak, and you should call a professional.
DIY vs Professional Costs
| Repair Type | DIY Cost | Professional Cost | Time Required |
|---|---|---|---|
Thawing the Coil & Replacing a Filter | $10-50 | $75-150 | 1-4 hours |
Cleaning a Lightly Dusted Evaporator Coil | $10-50 | $200-500 | 2-3 hours |
Refrigerant Leak Search & Recharge | NOT A DIY JOB | $350-1,000+ | 2-5 hours |
Blower Motor & Capacitor Replacement | $50-300 | $450-1,200+ | 2-4 hours |
Evaporator Coil Replacement | NOT A DIY JOB | $1,500-4,000+ | 4-8 hours |
When to Call a Professional Hvac
- The coil refreezes after you've already thawed it and replaced the air filter.
- You suspect a refrigerant leak, which can be indicated by hissing sounds or oily residue on the copper lines.
- The blower motor is not running when you switch the thermostat fan to 'ON'.
- You are not comfortable working around the electrical and mechanical components of your HVAC system.
Prevention Tips
- Regularly replace or clean your air filter every 1-3 months, or even monthly during heavy use.
- Schedule annual professional AC maintenance to have coils cleaned and refrigerant levels checked.
- Keep all supply and return vents clear of obstructions like furniture, rugs, and drapes.
- Ensure the area around your indoor and outdoor units is clear to maintain good airflow.
Frequently Asked Questions
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