I have something i have not seen before. carrier 7.5 ton r-22 evap with 2 four ton txvs. One is icing at the manifold and the other is not. I replaced the icing valve and got same results. Anyone seen this before? Thanks. 5/8 liquid line splits into 2 1/2 inch lines, go into seperate txv and suction lines join at outlet of air handler to return to condenser in 1 1/8 line.