Carrier 17/19EX - Manual (Page 261)

Oil Differential Pressure/Power Supply Module Calibration (See Figure 48 .)
The oil reservoir in the 17EX machine is not common to cooler pressure. Therefore, a
comparison of pump output to cooler pressure could not be used to provide differential oil
pressure information. A different method has been developed.
Oil transmission sump pressure and oil supply pressure are fed to a comparator circuit on a
5V power supply board. The output of this circuit, which represents differential oil pressure, is
fed to the PSIO. The oil differential pressure is calibrated to zero PSIO (0 kPad) by selecting the
oil pressure input on the Service1 screen. Then, with the oil pump turned OFF and the
transducers CONNECTED, press ENTER to zero the point. No high end calibration is needed
or possible.
Click here for Figure 48 — Oil Differential Pressure/Power Supply Module