Is the chiller actually measuring DP via transducers or the like to determine if there's enough flow? Or is there a separate flow switch? Reason I ask is if so, could be something fouling the transducer, causing it to read low. Transducer itself could be reading low (if that is what the machine has).
Have you used a separate gauge to measure delta P...are there PT plugs on the inlet and outlet piping for this purpose?
Building Physics Rule #1: Hot flows to cold.
Building Physics Rule #2: Higher air pressure moves toward lower air pressure
Building Physics Rule #3: Higher moisture concentration moves toward lower moisture concentration.