Maintenance and Troubleshooting | 6-13
Plumbing Leak
To check for plumbing leaks, disconnect all power form the RCU and
pressurize the inlets. Apply a leak detecting liquid along the base of the
solenoids and any plumbing fittings. Repair any leaks found.
Solenoid Not Energizing
The solenoid drive signal is a 15 VDC signal. This is used to open the ap-
propriate calibration gas solenoid.
To test a solenoid valve:
Select the Inject Cal Gas option from the Calibrate Key menu to ener-
gize that solenoid.
Verify that the solenoid drive signal is present. Solenoids are open
when the drive signal is applied (cal gas flowing).
With the drive signal present, verify the proper flow. If no signal is
present, check the interconnecting wiring between the control unit
and the RCU. If wiring is correct, replace the Auto Cal Card.
If the solenoid drive signal is not present, it indicates a problem with
one of the solenoid valves. Replace the solenoid valve being sure that
the solenoid O-ring seals are properly positioned when you insert the
new valve.
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 energized, 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 the Inject Cal Gas option from the Calibrate Key menu.
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