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324
FORM 160.54-M1
ISSUE DATE: 10/25/2019
SECTION 34 - DIAGNOSTICS AND TROUBLESHOOTING
JCI COMPANY CONFIDENTIAL
JOHNSON CONTROLS
14 - Proximity probe Position (Not applicable to P
compressors and style "F" and later chillers with
“G, Q” and “H5-8” compressors)
15 - Solid State Starter/CM-2 MUX output Channel 0
16 - Solid State Starter/CM-2 MUX output Channel 1
17 - Solid State Starter/CM-2 MUX output Channel 2
18 - Solid State Starter/CM-2 MUX output Channel 3
19 - Solid State Starter/CM-2 MUX output Channel 4
20 - Solid State Starter/CM-2 MUX output Channel 5
21 - Solid State Starter/CM-2 MUX output Channel 6
22 - Solid State Starter/CM-2 MUX output Channel 7
23 - Refrigerant Level Position
24 - Stall Transducer Output (Chillers equipped
w/ Variable Geometry Diffuser)(Software
version C.MLM.01.14.xxx (and later) or
C.OPT.01.14.306 (and later))
25 - Stall Detector Board Output (chillers equipped
with Variable Geometry Diffuser only) (Soft-
ware version C.MLM.01.10.xxx (and later) or
C.OPT.01.10.302 (and later))
26 - Pre-rotation Vanes potentiometer Output (chill-
ers equipped with Variable Geometry Diffuser
but not equipped with Compressor Motor Vari-
able Speed Drive or Hot gas bypass) (Soft-
ware version C.MLM.01.10.xxx (and later) or
C.OPT.01.10.302 (and later))
27 - Remote Leaving Chilled Liquid Temperature
Setpoint (0 to 20mA or 4 to 20mA)
28 - Remote Current Limit Setpoint (0 to 20mA or 4
to 20mA)
29 - Condenser Flow Sensor (Style F and later
chillers until June 2009. After September 2010,
Leaving Chilled Liquid Temperature Thermistor
on Heat Pump applications)
30 - Evaporator Flow Sensor (Style F and later chill-
ers until June 2009)
Procedure
1. From the list above, select the Analog Input Chan-
nel that is malfunctioning. All inputs except chan-
nel 0, 15 through 22, 27 and 28 are sensors that
connect directly to the microboard via shielded
cable. Channel 0 is a reference voltage for the
Analog circuits on the microboard. Channels 15
through 22 are multiplexed outputs from the Solid
State Starter (Solid Sate Starter applications) or
CM-2 Current Module (Electromechanical Starter
applications). Channels 27 and 28 are Remote
setpoint inputs used in Analog Remote Mode.
2. Refer to the appropriate Wiring Diagrams listed in
front of this manual to identify the device that per-
forms this function and the jack and pin connection
to the microboard.
Channel 0
Using a Voltmeter, measure the voltage between
Microboard TP6 (+2.5 VDC) and TP1 (GND).
Compare this measured value to the displayed
value. If the value is not within plus or minus
10%, replace the microboard.
All channels except 0, 1, 15-22
Using a Voltmeter, measure the Analog Input to
the microboard. Make the measurement between
the device output and ground connection to the
device. For example, measure the output of the
Evaporator Transducer at Microboard J8-18 (sig-
nal) to J8-9 (GND).
Channels 15-22
Select the desired channel by pressing the SE-
LECT CHANNEL key and using the
◄
and
►
keys to place the arrow head next to the desired
channel. Then, freeze the address of that chan-
nel to the Solid State Starter or CM-2 MUX.
Then measure MUX output at Microboard J10-6
(signal) to J10-5 (GND). When completed, press
CANCEL FREEZE key.
Channels 27, 28
IMPORTANT!
This procedure only
applies to 4 to 20mA inputs. It does not
apply to 0-10 VDC inputs. Using a Volt-
meter, measure the Remote Current Limit
setpoint input at J22-2 (signal) or Remote
Leaving Chilled Liquid Temperature
setpoint input at J22-4 (signal) to J22-5
(GND).
3. Compare the measured value in the previous step
with the value displayed on the ANALOG IN-
PUTS Screen for that value.