Hello, I've been racking my brain trying to figure this one out. Last night I went on an emergency service call for a huge data center thats got a 6 of these floor mounted VHS Stulz units. Anyway There was one all the way in the back both circuits frozen from the spreader tubes of the txv's all the way back to the compressors (copeland Scrolls). Of course I disabled the compressors and let the blower run to thaw the coil out before I took any pressures and tems. To be noted Circuit #1 actually had a frozen TXV body where as circuit 2 just had fronzen speader tubes. Anyway after defrosting I noticed that circuit number 1 had a much lower suction (52psi) than circuit 2(71 psi). Both circuits were maintaing about 16 degrees super heat and circuit number one had 27 degrees subcooling, circuit 2 17. I think the low pressure in circuit one is causing low refrigerant Temp, even though maintaining superhead and eventually is frosting up the coil, inevitably affecting circuit 2. Once I got it going again I had 55 degree discharge air and 82 return air. Checked filters and even made sure the re-heat slab coil on top of the A-coil was free of debree. Poor airflow under floor due to cables on top of cables in the cold Isle. TXV on circuit one was recently replaced as well and so was drier. checked for restriction at drier, found none. Can't figure out why the nearly 20 psi difference in Compressor number on suction. Any help would be appreciated.