[johnkosir]

When you turned off your 120 volt compressor that caused your 12 volt to turn on. The 120 volt compressor tank,  will supply air to the 12v tank through a check valve , The 120 has a higher turn off pressure so if it is working the 12 volt does not turn on. On 712 there is a check valve that stops the air from the 12 volt from leaking out of that water separator. That might be your only leak or you might have another one.