Thanks again to Jayguy for the manual for a Trane CGAC chiller.
While it was hard to come by, it was worth the wait. I have to say that the manual has one of the clearest presentations of the theory of ops for any owner/operator manual I've seen.
Excellent piece of work.
I continue apace with my plan to replace a bad compressor with an equivalent scroll and I'm wondering if there is enough internal volume difference in the compressor designs to make much difference in the target charge.
also, i have a suspicion regarding the thermostatic expansion valve being blocked or inaccurate on the other circuit -- although i am thinking that a stuck compressor valve might give similar symptom.
The manual calls for testing the TEV in the event of the exhibited symptoms (low discharge and suction pressures. While my first instinct was a minor leak and low charge, I'm getting no bump on the discharge out of the compressor so the system is blocked somewhere. I'm more suspicious of the compressor itself ,but the manual (and despite all the good things I said about it) doesn't suggest any method for testing TEV. I can figure out if its blocked but I'm not sure how to test its range of response to various superheat readings.