I need help, R22 18 Ton Rheem 2 stage 3 phase unit with a frozen low side problem...

One of the compressors is running at 15 Superheat and seems to have no problem at all..

The second compressor's low side keeps freezing up and therefore affects compressor 1.

Here are some stats taken earlier today...
Dry bulb 92F

27.3 Degrees on Low Side / 51 Psi
154 Degrees on High Side / 340 Psi
Superheat approx 5

The pressure was lower on the high side when I first got there and when I added freon it got up to 350, the low side temperature does not seem to improve at all with the added refrigerant..

I have checked the evaporator, clean, no restriction on the return...

Any Ideas?