After cryogroup (Robert Norton) informed me that it was ok to start 15K cool-down, we re-started the cooldown process. When MCC opened the 15K supply valve,, before I opened the J-T valves for loops 1 and 2, I noticed a large value of cryo-flow. Loop 3 (un-used) J-T was open. I asked MCC to close the supply valve. Since I could not control the loop 3 J-T either from the GUI or from the control box downstairs. After talking to Dave Meekins. I checked around the control box. Turned out the control cable was unplugged. I plugged it back and completely closed the J-T fro loop 3. And unplugged it again (to prevent anybody accidentally open it. We now just re-started the cool-down.