The short answer
Ice on the copper lines or the indoor coil means the coil is freezing. The cause is airflow or charge: a dirty filter or evaporator coil, a blower that is not moving enough air, or a refrigerant charge that has dropped.
What you can check yourself
- Turn the thermostat to Off, and set the fan to On so the ice melts. Do not chip it off.
- Check and replace the filter if it is dirty.
- Wait until it has melted before you try the system again.
- If the ice comes back, leave it off and call.
What gets checked first
- Filter and the evaporator coil
- Blower motor and belt
- Refrigerant charge, and where it went
Repair or replace?
A repair if it is airflow. If it is a leak on an old system, we talk about both options.
When to call now
A system left running while it is iced up can be damaged. Turn it off.