Large insulated Central A/C pipe freezing

[songiuno]

I read this post (http://www.terrylove.com/forums/showthread.php?t=21786&highlight=a%2Fc+pipe+freezes) about the smaller of the two central A/C pipes connecting to the condenser freezing. What does it mean when the larger, the insulated one, pipe freezes? I noticed this morning that the house was getting hotter and the fan wouldn't come on, so I went outside to look at the exterior unit and saw the following (photos).

Can someone tell me if there's something I'm doing or not doing that would cause this? I change my filters close to monthly (sometimes goes 2 months) but otherwise I'm not sure what else might be wrong.

[gator37]

I have not messed with these problems in about 40 years but a good service person may correct me but
When you say the fan does not come on are you talking about the indoor fan or the condenser fan?

Indoor fan not working typically will cause the indoor coil to freeze
(assuming the rest of the system is working), not sure if it would freeze all the way back to the condenser or not.

Frost on the suction line can also indicate low gas

If heat pump it could be the reversing valve is stuck or not functioning.

Sorry that is about all I remember