14
Single-Duct and Retrofit Terminal Units IOM
ANALOG CONTROL TROUBLESHOOTING
The following troubleshooting guide is directed towards
single duct cooling applications, the same concepts can be
applied to other configurations.
NOTE:
For about 15 seconds after power is applied, no
rotation occurs and one or both of the controller/actuator
LEDs will flash.
Controller
1. Check that the shaft moves freely. (Press and hold the
actuator release clutch and manually rotate the shaft.)
2. Check wiring. (See Wiring Issues section below.)
3. Check for a tripped circuit breaker to the transformer, for
proper supply voltage from the transformer (or power
supply), and for enough capacity (VA) for all connected
devices.
4. Check that the direction jumper is in the proper position
per individual controls submittal.
5. Check the polarity and level of the input signal from the
thermostat.
Wrong Rotation Direction or Stroke Range
1. Check the position of the direction jumper.
2. Check the Min and Max flow limits on the thermostat
(AO1 / AO2).
3. Check the adjustable mechanical stop position.
No Pressure Output Signal from Inlet Sensor
1. Check the tubing. Tubing should be free of kinks and
restrictions.
2. Check air flow and sensor. Sensor must be oriented in the
correct airflow direction and free of large debris.
Wiring Issues
1. Check for correct wiring at unit and thermostat per
individual controls submittal.
2. At the Controller, verify 24 VAC at terminals “~” (phase)
and “-” (ground). Tolerance can be –15% to +20% (20.4 to
28.8 VAC).
3. Verify 16 VDC at terminals “16 VDC” and “COM”.
a. Tolerance is 15.0 to 17.0 VDC power supply to
thermostat.
b. If not correct, disconnect thermostat and recheck.
c. If still incorrect, replace CSP controller.
4. Check “Requested Flow” DC voltage on terminal “2-10 IN”
and “COM“.
a. Use Table 4 to correlate into cubic feet per minute
(CFM).
b. If reading is not what is desired, then adjust
thermostat to give correct CFM.
NOTE:
Never jumper terminal 16 VDC to “-” as this would
cause a short, and possibly damage the power supply.
NOTE:
When using the same transformer for more than one
control, the phase and ground must be consistent with each
device.