Pressure Transducers - Carrier FLOTRONIC II 30GN040-420 Operating And Troubleshooting Manual

LEGEND
DPT — Discharge Pressure Transducer
EXV — Electronic Expansion Valve
OPT — Oil Pressure Transducer
SPT — Suction Pressure Transducer
T — Thermistor Number
Pressure Transducers —
transducer is used for both high- and low-pressure sensing
on Flotronic™ II chillers. However, this transducer must be
calibrated before the unit will operate. On new units, this
will have been done at the factory in order to test run the
unit. If a transducer or PSIO is replaced in the field, how-
ever, the transducer will have to be field calibrated as
follows:
1. Disconnect transducer from the system.
2. Hang the transducer in the atmosphere.
3. Press on the HSIO keypad, and Read the pres-
sure. Pressures before calibration must be within the
range of 5 psig. If the pressure is outside the range of
5 psig, the HSIO display will read ---. If this is the
case, replace the transducer or PSIO or check for a wir-
ing error. If the value of the atmospheric pressure is greater
than 5 psig or less than –5 psig, the transducer will be
considered out of range and will not calibrate.
Fig. 14 — Thermistor and Pressure Transducer Locations
A single style of pressure
4. Press on the HSIO keypad. This automatically ap-
plies the proper correction factor to all future inputs from
the transducer.
Three pressure transducers are mounted on each lead com-
pressor: 2 low-pressure transducers to monitor compressor
suction pressure and oil pressure, and a high-pressure trans-
ducer to monitor compressor discharge pressure (see
Fig. 17 for exact locations on compressor). Each transducer
is supplied with 5 vdc power from a rectifier which changes
24 vac to 5 vdc.
TROUBLESHOOTING — If transducer is suspected of be-
ing faulty, first check supply voltage to transducer. Supply
voltage should be 5 vdc ± .2 v. If supply voltage is correct,
compare pressure reading displayed on keypad and display
module against pressure shown on a calibrated pressure gage.
If the 2 pressure readings are not reasonably close, replace
pressure transducer.
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