Review on ACDelco GM Original Equipment 15-72972 Temperature Valve Actuator: Reliable Control for Optimal Temperature Regulation by David Pullen

If installed with a genuine ACDelco 15-73506 GM A/C Control Module, connect the actuators first, then the module. Or, if a new module is already installed or the old one is working, disconnect the terminals on the existing module. Then reconnect the module terminals and perform a system reset including removing the 10A fuse as shown online. Otherwise it may result in the module not being able to control the actuators and this may explain why some people describe having new non-working actuators. Much luck.