We have discovered a low flow condition on a couple of our machines that appears to be back pressure from the return line. I get very good flow when the circuit is open looped(3 gpm), but when close looped it drops to .6 GPM. This is on a circuit that is not running through the mold only a line running from one manifold to the other.

Any thoughts on what to check? The machine next to it has +2 gpm under the same closed loop condition so it points me toward the temperature control unit more than the system, but I'm sort of running out of ideas.