JOHNSON CONTROLS
210
FORM 150.67-NM1
ISSUE DATE: 4/28/2017
SECTION 9 – SERVICE AND TROUBLESHOOTING
The suction transducers have a range from 0 to 400
PSIG (27.5 barg). The output will be linear from
0.5VDC to 4.5VDC over the 400 PSIG (27.5 barg)
range. Following is a formula that can be used to verify
the voltage output of the transducer. All voltage read-
ing are in reference to ground (unit case).
V = (Pressure in PSIG x .02) + .5
or
V = (Pressure in barg x .29) + .5
where V = DC voltage input to microprocessor
Pressure = pressure sensed by transducer
Following are the I/O board connections for the Suc-
tion Transducer.
System 1 Suction Transducer
J7-5 = +5VDC regulated supply to transducer.
J7-10 = VDC input signal to the microboard.
See the formula above for voltage readings that cor-
respond to specific suction pressures.
J7-9 = +5VDC return.
J7-1 = Drain (shield connection = 0VDC).
System 2 Suction Transducer
J9-5 = +5VDC regulated supply to transducer.
J9-10 = VDC input signal to the microboard.
See the formula above for voltage readings that cor-
respond to specific suction pressures.
J7-9 = +5VDC return.
J7-11 = Drain (shield connection = 0VDC).
Digital Outputs
Refer to the unit wiring diagram and Figure 60. The
digital outputs are located on TB7, TB8, and TB9
and TB-10 of the microboard. ALL OUTPUTS ARE
120VAC with the exception of TB8-6 to TB8-7 which
are the contacts that can be used for a remote evapora-
tor pump start signal. The voltage applied to either of
these terminals would be determined by field wiring.
Each output is controlled by the microprocessor by
switching 120VAC to the respective output connection
energizing contactors, evaporator heater, and solenoids
according to the operating sequence (see Figure 60).
The I/O board is supplied with 120VAC via connec-
tions at TB7-1, TB7-6, TB10-1, TB10-6, TB8-1 and
TB9-1. Figure 60 illustrates the relay contact archi-
tecture on the microboard.
FIGURE 60 - I/O BOARD RELAY CONTACT
ARCHITECTURE
LD12722
SYS 1
COMP 1
TB7-2
SYS 1
COMP 2
TB7-4
SYS 1
COMP 3
TB7-5
TB7-3 LLSV 1
TB8-6
EVAP
PUMP
TB8-7
TB7
SYS 2
HGSV
TB10-7
SYS 2
FAN 2
TB10-8
TB10-9
TB10-10
SYS 2
FAN 4
TB10
TB8
TB10
SYS 2
COMPR 1 (4)
TB10-2
LLSV 2
TB10-3
SYS 2
COMPR 2 (5)
TB10-4
SYS 2
COMPR 3 (6)
TB10-5
TB7
SYS 1
HGSV
TB7-7
SYS 1
FAN 1
TB7-9
SYS 1
FAN 3
TB7-10
TB7-8
SYS 1
FAN 2
TB8-2
HEAT EXCH
HEATER
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