Ametek Thermox WDG-V UOP, User Manual

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Troubleshooting | 5-7
To check if a
calibration gas
solenoid is stuck
open:
Verify that no drive signal is present and check for flow on the
RCU flow meter.
If flow is indicated when no solenoids are ener -
gized, a solenoid is stuck open.
Shut off your calibration gases
(one at a time) until the flow drops to zero. This identifies the
defective solenoid valve (replace the solenoid valve, being sure
that the solenoid O-ring seals are properly positioned).
Calibration Gas
Time Inadequate
If you are having problems running an auto calibration, you
may not have allowed the calibration gases enough time to flow
through the sensor and stabilize. To correct this problem, select
Inject Cal Gas from the Diagnostic menu.
Turn on each calibration gas and determine how long it takes
for each gas to stabilize on the control unit display. Then add a
one minute buffer to each of these times. Also make sure the
cylinder regulators are set to the correct pressure. See the Flow
Section of the System Interconnect Drawing for the system flow
and pressure requirements . This drawing is included with your
Installation package.
Select
Cal Gas Duration from the Calibration menu to set cali-
bration gas times.
If performing a manual calibration, ensure that you are waiting for
the reading to stabilize on the display before switching to the next
calibration gas.
AC Power Checks
Loss/Inadequate AC Voltage
to the Sensor
Measure the AC voltage to the sensor board at terminals L and
N. Ensure that this voltage is sufficient. Check the measure -
ment technique used by the Volt meter (for example, RMS,
average, peak, etc.). Specifications are based on RMS mea -
surements.
Furnace Checks
Open Furnace
Disconnect power to the control unit and the sensor. With Ohm
meter, measure across Terminals “FURN” on the connector. At
room temperature, the resistance should be:
115 VAC furnace coil: 49 ohms
230 VAC furnace coil: 177 ohms
If the furnace resistance is open, replace the furnace.
Loss of AC Power
to the Furnace
Verify the correct line voltage at L and N of the sensor board.
With line voltage present, check the voltage at terminals FURN
on the sensor board. If voltage is present and the system is not
heating, remove power and check the furnace resistance (see
“Furnace Checks” section). If no voltage is present at terminals
FURN on the sensor board, replace the electronics.