The control box will state "No Coil" when the "handshake" has not been completed for whatever reason.
When first charging the coil the light should be on constantly. When the charge is complete the light will alternate by being ON for 3 seconds then OFF for 3 seconds and so forth.
You say you are sure it should flash "every 30 seconds or so" ... where did you get this information?
Does it flash every couple of minutes? If so you may have a bad connection.
Make sure the contacts are exceptionally clean on the coil as well as the charger pins.
Try another charger clamp if you can....
If that fails, you may have a faulty coil.
Hope you get it sorted
