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Wall controller
T
o check the output circuit continuity,
remove the “4–20 mA output” wires at the wall controller, and then measure
the same 250-ohm input impedance plus the resistance of the cable used for installation on the output circuit
wiring.
Note: The analog current input on the VFD has an input impedance of 250 ohms. Measure this value at
the analog input terminals of the VFD (terminals ACM-ACI).
To check the output circuit current,
remove power from the wall controller. Place a multi-meter (set to mA DC)
in line with one of the mA output conductors. Reapply power. Set the wall controller to Manual Mode. The loop
current should be between 4mA–20mA in accordance with the speed adjustment buttons on the wall controller
keypad.
Note: The wall controller provides a 4–20mA current to the VFD for speed reference.
Wall Controller Troubleshooting
During operation, the auxiliary controller keypad display will typically show the command frequency from the wall
controller. If the display reports the error code shown below accompanied by fan shutdown or slowdown, one of
the following conditions has occurred:
• The 4–20 mA loop circuit between the VFD and the auxiliary controller has failed. Remove system power and
check for short circuits and/or open circuit conditions. See below for more information.
• The wall controller power has been removed during normal operation. Check +24 VDC power supply and
associated connections.
• Component failure at the auxiliary controller or at the VFD. See below for more information.
Fan Keypad “Analog Error”
RUN
STOP
FWD
REV
REM
LOC
U
H
F
Upper temperature sensor
To check the output circuit current,
remove power from the wall controller. Place a multi-meter (set to mA DC)
in line with one of the remote’s conductors. Reapply power. The upper temperature sensor signal should read
between 4–20 mA DC. This reading can be converted to degrees Fahrenheit using the following formula:
Degrees F = 18.7 x mA - 74
Example: 86° F = 18.7 x 8.55 mA - 74
Note: Because the load impedance of the upper temperature sensor is in excess of 1 Mohm, the best way to test
the upper temperature sensor is to measure the mA signal from the sensor while the system is in operation.
