Site had a BMS replacement last month. Since then one of three chillers short-cycles on light load, mostly evenings and weekends. Trips on low delta-T, restarts a few minutes later. The other two run normally on the same header.

Contractor says it is a chiller fault. Chiller vendor says it is a controls issue. Both are technically not wrong, which is the problem.

What we have checked so far: flow rates through the evaporator, secondary pump minimum speed, and the staging setpoints in the new BMS. Delta-T sits around 2.5K at light load against a design 6K.

Before I escalate this commercially, has anyone dealt with the same after a controls handover? Interested in what turned out to be the actual cause.