from the transducer by th e supply voltage signal, measured at the PSIO ter m ina ls J7-J34
and J7-J35. For examp le, the condenser transduc e r voltage input is meas ur ed at PSIO ter-
minals J7-1 and J7 -2. The voltage rat io must be betwe en 0.80 vdc and 0.11 vdc for the soft-
ware to allow calibrat io n. Pressurize the tran sducer until the ratio is wi th in range. Then
attempt calibratio n again.
4. A high pressure point ca n als o be calibrated betwee n 240 and 260 psig (1655 and
1793 kPa) by attachi ng a r eg ulated 250 psig (1724 kPa) pr e ssure (usually from a ni trogen
cylinder). The high pr e ssure point can be calib r at ed by accessing the tran s duc e r on the
Status01 screen, highlighting the transducer, pressing the SELECT softkey, and then
increasing or decreas i ng the value to the exact pr es s u re on the refrigerant ga ge. Press
ENTER to finish. High al titude locations mu s t com p ensate the pressure so tha t the
temperature/pressure relationship is correct.
If the transducer rea din g returns to the previ ous v al ue and the pressure is wit hi n the
allowed range, check the voltage ratio of the tra nsducer. Refer to Step 3 above. The voltage
ratio for this high pre s s ur e c al ibration must be betw een 0.585 and 0.634 vdc to al low cali-
bration. Change th e pressure at the transd ucer until the ratio is within the acceptabl e range.
Then attempt calibra te to the new pressure inp ut .
The PIC will not allow calib ration if the transducer is t oo far out of calibration . A new
transducer must be inst al led and re-calibrat ed.