Return air 3.0 °C above its 24 °C band with the chilled-water valve at 100% — the unit is giving all it has. Chilled water is arriving warmer than design and leaving only 6 °C warmer.
Could be
- Chilled water arriving too warm (plant or secondary pump)
- Low water flow: blocked strainer or throttled balancing valve
- Air lock in the coil
- Fouled coil or blocked filters
- Load above design (occupancy, open doors, fresh air)
- Return-air sensor reading high (calibration)




