Primary Diagnostic Causes & Field Remediation
Restricted Airflow / Dirty Filter
When dust blocks the intake grill or evaporator fins, cold air cannot circulate into the room, driving coil surface temperatures below freezing.
Low Refrigerant Charge
Contrary to intuition, low refrigerant lowers suction pressure, causing the remaining refrigerant to boil at sub-freezing temperatures at the coil inlet.
Vapor Barrier Breach
If warm humid outside air infiltrates through walls or unsealed electrical outlets, excessive moisture overwhelms the coil surface.
Frequently Asked Questions
Should I scrape the ice off the evaporator coil?
NO. Never use sharp tools to scrape aluminum fins. You risk puncturing copper refrigerant tubes. Turn the unit to FAN ONLY or OFF and let it melt naturally.
Will the ice come back after melting?
Yes, unless the root cause (air filter, refrigerant leak, or fan motor) is professionally repaired by a certified HVAC-R technician.