A/C Lines Freezing

I think you'll find it isn't your lines freezing... it's probably your evap icing up. Make sure your dash housing drains aren't clogged.

 

I'm not certified in A/C but believe the problem likely low freon... I know it sounds backwards but that was what fixed mine.

 

We have a 2005 Columbia ours was doing that, we also check system for freon and leaks but it's the thermostats probably need to be replaced on its there is two of them it's about a $400 job, the thermostats are only $40 a piece from freightliner it's all in the labor.

 

Check the in-cab air filter and coil make sure they are clean if either or both if them are dirty it will cause a freeze up and poor cooling due to lack of air flow also check the consider big radiator looking thing infront of the actual radiator if it gets plugged up with bugs and dirt that will cause freeze up and poor cooling aswell ac is all about air flow if the system is working properly

 

What thermostats?

There are expansion valves or orifice tubes that are used.

I am thinking that if your evaporator is freezing up, as mentioned it has a lot of water or moister in the unit and the drains are plugged.