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C
heckout Procedure
Before applying power, make sure installation and
wiring connections are according to job specifications.
After necessary adjustments and electrical
connections have been made, put the system in
operation and observe at least three complete
operating cycles before leaving the installation.
T
roubleshooting
If the control system does not function properly, first
verify that the control, power, and display modules are
all operating correctly (refer to the respective
literature). Then inspect the stage modules for proper
operation.
Check that the proper operating mode
(Cooling/Heating, Dehumidification/Humidification, or
Direct Acting/Reverse Acting) has been selected on
each stage module. (See Adjustments section and
Figures 3, 4, and 5.) Then perform the following
procedures to determine the problem.
1. Verify the system has power.
2. Note the offset and differential settings on the
stage module.
3. Turn the setpoint dial on the control module to
minimum.
4. Increase the setpoint by slowly adjusting the
setpoint dial until the stage relay LEDs turn On
and Off as shown in Tables 3, 4, or 5.
Table 3: S350A Relay Troubleshooting
Operation
LED
Mode
Cooling
On
Cooling
Off
Heating
On
Heating
Off
*(T
) = sensed temperature
s
S350A Temperature, S351A Humidity, and S352A Pressure Stage Modules Product/Technical Bulletin
N.O.
Setpoint Dial
Relay
Setting
Status
Closed
(T s )* - offset
- differential
Open
(T s ) – offset
(T s ) + offset
Closed
+ differential
Open
(T s ) + offset
Table 4: S351A Relay Troubleshooting
Operation
LED
Mode
Dehumidify
On
Dehumidify
Off
Humidify
On
Humidify
Off
*(RH
) = actual relative humidity at transducer
T
Table 5: S352A Relay Troubleshooting
Operation
LED
Mode
Direct
On
Direct
Off
Reverse
On
Reverse
Off
*(psi
) = actual pressure at transducer
T
5. If the relays do not perform as indicated in
Tables 3, 4, or 5, adjust the stage module's
differential and offset potentiometers to minimum
and repeat Steps 1 through 3.
6. If the relays still do not turn on and off, replace the
defective stage modules.
Note:
There is the unlikely possibility that a defect in
one stage module could cause defective
symptoms in all modules. Plug each stage into
the control individually and check the
performance of each as explained above.
R
epairs and Replacement
Do not make field repairs or perform calibration.
Sensors and replacement controls are available
through your local Johnson Controls representative.
N.O.
Setpoint Dial
Relay
Setting
Status
Closed
(RH
)* -offset
T
- differential
Open
(RH
) - offset
T
Closed
(RH
) + offset
T
+ differential
Open
(RH
) + offset
T
N.O.
Setpoint Dial
Relay
Setting
Status
Closed
(psi
)*- offset -
T
differential
Open
(psi
) - offset
T
Closed
(psi
) + offset +
T
differential
Open
(psi
) + offset
T
7
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