Solenoids and Large Relays create a lot of interference, this can wreak havoc to nearby electronic devices. If you notice the sound is stopping unexpectedly when controlling one of these devices this is most likely your problem. For AC solenoids you need to use a capacitor, the best place to install it is as close as possible to the solenoid, if that's not possible then across the terminal block on the controller may work as well. You can get these capacitors from FrightProps.
WARNING: HYDRAULIC AND PNEUMATIC POWER SYSTEMS CAN FAIL THROUGH MISUSE, AGE OR MALFUNCTION. THE SYSTEM DESIGNER
IS WARNED TO CONSIDER THE FAILURE MODES OF ALL COMPONENTS USED IN THE DESIGN AND ENGINEERING OF ALL SYSTEMS AND TO PROVIDE ADEQUATE
SAFEGUARDS TO PREVENT PERSONAL INJURY OR DAMAGE TO EQUIPMENT IN THE EVENT OF SUCH FAILURES