See this article for general troubleshooting (includes schematic and call-outs), 7615 Schematic and Drawing for Troubleshooting
Use the below procedure to purge air from the 7615 controller
- Check supply pressure: Air supply should be regulated between 90-100 psi.
- Remove top enclosure of 7615 controller so you can watch the pump discharge (make pressure) and recharge.
- With the system vented and the TEST port plugged, loosen the gland but do not remove it.
- Set the unit to control at 10% FS. (Note: Once you start controlling, fluid should start coming out of the loose fitting).
- Before the pump recharges tighten the gland. Failure to tighten the gland before recharging will re-introduce air into the unit.
- Repeat step 1-3 until all air has been removed.
If you don't get any oil and the pump is moving back/forth then you might need to loosen fittings closer to the pump per the below image. Loosen the fittings in sequence; 1, 2, 3. Do not let the pump recharge while a fitting is loose or air will be sucked into the system.