If the transducer val ue is not within the calibra tion range, the trans du cer will return to the
original readin g. If the LID pressure value is within t he allowed ra nge (noted abov e), check
the voltage ratio of the t ransducer. To obtain the voltage ratio, divid e the voltage (dc) inp ut
from the transducer by th e supply voltage sign al, measured at the PSIO te r m ina ls J7-J34
and J7-J35. For examp le, the condenser trans duc e r voltage input is mea s ur ed at PSIO ter-
minals J7-1 and J7 -2. The voltage r atio must be betwe en 0.80 vdc and 0. 11 vdc for the sof t-
ware to allow calibrat io n. Pressurize the tran sducer until the ratio is within 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 kP a) pr e ssure (usually from a ni trogen
cylinder). The high pr e ssure point can be calib rated by accessing the transducer 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 refrigeran t ga ge. Press
ENTER to finish. High al titude locations mu s t com p ensate the pressure so that 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 hin 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 accept able range.
Then attempt calibra te to the new pressure inp ut.