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Control Service and Troubleshooting
ANALOG INPUTS – Pressure
Refer to the unit wiring diagram. Pressure inputs are
connected to the microboard on plugs J4 and J7. These
analog inputs represent varying dc signals correspond-
ing to varying pressures. All voltages are in reference to
the unit case (ground).
System 1 discharge and suction pressures will be con-
nected to J4 of the microboard. System 2 discharge and
suction pressure transducers will be connected to J7 of
the microboard.
The discharge transducers are optional on all units. If
the discharge transducers are not installed, no connec-
tions are made to the microboard and the discharge pres-
sure readout on the display would be zero.
The suction pressure transducers are optional on
YCUL0045 - YCUL0185. If the suction transducers are
not installed, a mechanical low pressure switch will be
installed in its place, and the suction pressure readout
on the display will be 0 PSIG when the LP switch is
open, and 200 PSIG (13.79 BARG) when the LP switch
is closed.
The discharge transducers have a range from 0 to 400
psig. The output will be linear from .5 VDC to 4.5 VDC
over the 400 PSIG (27.5 BARG) range. Table 32 shows
the formula that can be used to verify the voltage output
of the transducer. All voltage reading are in reference to
ground (unit case).
TABLE 32 – DISCHARGE PRESSURE TRANSDUCER
PRESSURE TO VOLTAGE
CONVERSION FORMULA
V = (Pressure in PSIG x .01) + .5
– or –
V = (Pressure in BARG x .145) + .5
where V = DC voltage output
Pressure = pressure sensed by transducer
The microboard connections for the Discharge Trans-
ducers:
System 1 Discharge Transducer
J4-7
= +5 VDC regulated supply to transducer.
J4-12 = VDC input signal to the microboard. See Table
32 for voltage readings that correspond to spe-
cific discharge pressures.
J4-8
= +5 VDC return
J4-9
= drain (shield connection = 0 VDC)
136
System 2 Discharge Transducer
J7-7
= +5 VDC regulated supply to transducer.
J7-12 = VDC input signal to the microboard. See Table
32 for voltage readings that correspond to spe-
cific discharge pressures.
J7-8
= +5 VDC return
J7-9
= drain (shield connection = 0 VDC)
The suction transducers have a range from 0 to 200 psig
(13.79 BARG). The output will be linear from 0.5 VDC to
4.5 VDC over the 200 psig (13.79 BARG) range. Follow-
ing is a formula that can be used to verify the voltage
output of the transducer. All voltage readings are in refer-
ence to ground (unit case).
TABLE 33 – SUCTION PRESSURE
TRANSDUCER PRESSURE TO
VOLTAGE CONVERSION FORMULA
V = (Pressure in PSIG x .02) + .5
– or –
V = (Pressure in BARG x .29) + .5
where V = DC voltage input to micro
Pressure = pressure sensed by transducer
Following are the microboard connections for the Suc-
tion Transducer:
System 1 Suction Transducer
J4-5
= +5 VDC regulated supply to transducer.
J4-10 = VDC input signal to the microboard. See Table
33 for voltage readings that correspond to spe-
cific suction pressures.
J4-1
= +5 VDC return
J4-2
= drain (shield connection = 0 VDC)
System 2 Suction Transducer
J7-5
= +5 VDC regulated supply to transducer.
J7-10 = VDC input signal to the microboard. See Table
33 for voltage readings that correspond to spe-
cific suction pressures.
J7-1
= +5 VDC return
J7-2
= drain (shield connection = 0 VDC)
If the optional Suction Transducer is not used on the
YCUL0045 - YCUL0185, a Low Pressure switch will be
used. Following are the microboard connections for the
Low Pressure switch.
YORK INTERNATIONAL
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