Hello, my question is will a dirty filter cause ice to build up on my lines running to the outside a/c unit. I also noticed I need to re-insulate the line outside as it is cracked and weathered. My wife said she noticed freezing and ice at points where the insulation was cracked.

You bet. A dirty filter will restrict airflow and that is one of the major reasons the unit will freeze up. I bet the evaporator is iced over as well. It will need to thaw before colling and airflow will return to normal.

The insulation on the outside pipe (AKA armaflex) is an easy fix but had nothing to do with unit freezing up. A/C's freeze for 2 reasons


Reduced airflow. ex. dirty filters blocked registers and returns, dirty coil or secondary heat exchanger, incorrect blower spped or failing blower motor.
Low on refregerant


If you don't think the filter wasn't to bad you might want to call a service tech and check the charge. It will be way worth it in the end.