I've had mine clog up twice, both in late spring/beginning of summer. After hooking up and turning the water on, I got a little water, some hissing and then nothing. One time I still had RV antifreeze in the lines and the other time I had flushed the antifreeze out a couple of weeks before.
'01 2500hd ext. cab, 8.1 litre gas, 5 sp. Allison auto
3.73 rear end
Mag-Hytec rear diff cover
Amsoil Dual by-pass oil filtration system
Amsoil synthetics all around
265 watt AM Solar, Inc. system