Installation required extravehicular operations. Environmental control Thermal control system Leakage of coolant fluid from coolant loop. Fluid replenished on third visit. Refrigeration system Failed primary and secondary refrigeration system loop bypass valves in partial radiator position caused low loop temperature and loss of control. Connector J5 disconnected to permit simultaneous use of primary and secondary loops and to prevent automatic switchover.
Gas bubbles in cooling fluid caused flow rate fluctuations.
Valve resumed operation during troubleshooting. Life support Orbital Workshop hatch check valves Check valves leaked. Check valve orifices taped. Vent valves remained open after close commands sent. 150-psi nitrogen pressure regulator Nitrogen pressure regulator was 10 to 15 psi low.