Frequently Asked Questions –
Start-up Procedures & Adjustment


I have installed the APR Control; now what are the steps I need to take after evacuating the system?

Make sure the APR Control was open to the circuit during evacuation. Prior to charging the system you should isolate the APR Control out of the system with the three isolation valves (closed). You will need to have the APR Control isolated during the charging of the system and the system should be run initially with the APR Control entirely out of the circuit (isolation valves remain closed). This is necessary to make sure the charge is correct and that the air conditioning system is operating as originally designed, and so there is a baseline to measure the system “with the APR Control modulating” against. In addition, there is the benefit of allowing the system filter/dryer to clean the refrigerant before it is allowed to enter the APR Control. This helps ensures for the cleanest startup possible.

Will I need to adjust the APR Control?

The APR Control is shipped from the Factory set for approximately 40 degrees F. evaporator coil temperature, or to start opening at 118psi (in an R-410A system). Most application will not require adjusting the APR Control. But if the runtime is inadequate or low load operation does not cause suction pressure to fall low enough, you may need to adjust the APR Control hot gas valve. Please call Rawal Devices Engineer’s (800-727-6447) at the factory prior to attempting any adjustment.

Is there any adjustment required for the desuperheating injection valve?

No, NORMALLY YOU WILL NEVER TOUCH THE INJECTION VALVE. If you believe there is any need to adjust the desuperheating injection valve, please call Rawal Devices Engineer’s (800-727-6447) at the factory prior to attempting any adjustment.