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DN-Series Integrated Programmable Controls
DOAS
90
TROUBLESHOOTING
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For the fan that has the alarm (supply or exhaust), command the fan to run at 35% or so.
If you see the flow increase but don’t see the feedback (current switch) to yes, then the
problem is with the current switch. If you don’t see the flow increase the fan did not start and
the problem is either with the wiring or the VFD parameters.
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If you think the problem is with the current switch, try adjusting the fan % up until you
see the feedback go to YES. During this time, you should also see the flow to continue
to increase. Once you see the feedback turn to yes you know the current switch needs
adjustment. If it gets to 100% and you do not see it turn to yes, it may be wiring or a bad
current switch. You can try to adjust it below.
Adjusting the Current Switch
With the dampers open and the fans enabled as described in the Test End Devices mode
above, set the fan for which you want to calibrate to the minimum speed (%) at which you
expect it to operate.
On the top of the sensor, there are an adjusting screw and two LED lights, one red and one
blue. The adjusting screw will turn 15 turns. To set the sensor for any fixed-speed fan:
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Verify that the blue LED is on.
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Slowly adjust the potentiometer screw clockwise until the RED LED just turns on. This sets
the trip point at the normal operating load current
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If the RED LED is on after initial power-up, slowly adjust the potentiometer counter-clockwise
until the BLUE LED turns on and then slowly adjust the potentiometer clockwise until the RED
LED just turns on.
IMPORTANT
Cycle power to the unit after you are done testing. This will take the unit out of Device Test
Mode and reset all of the test values to off or 0%.
