ACORN ENGINEERING FIELD SERVICE
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INSTALLATION, OPERATIONS & MAINTENANCE MANUAL
®
MERIDIAN 3791-RO
Please visit
www.acorneng.com
for most current specifications.
TROUBLE SHOOTING FOR 9 VOLT DC SENSOR OPERATED VALVES
Normal Valve Function:
9 Volt DC sensor operated valve has flow time of 90 seconds maximum.
To reactivate, the user must move out of and return to the sensing area.
CONDITION:
WATER DOES NOT FLOW
Indicators
Probable Cause
Solution
Sensor flashes continuously
every 2 seconds when
hands are within range.
Low battery warning
Replace battery
Circuit breaker tripped.
Reset circuit breaker
Replace battery
Defective 9V DC transformer
Transformer polarity crossed
Replace transformer (sensor may be
damaged and need replacement).
Unit is in “Security Mode” after
90 seconds of constant detection.
Remove sources of detection and
wait 30 seconds before checking.
Range is too short.
Increase range.
Range is too long.
Decrease range and wait 30 seconds.
Sensor is picking up a highly
reflective surface.
Eliminate cause of reflection and wait
30 seconds before checking.
Sensor does not flash
when the user’s hands
are within range.
Defective sensor.
Replace sensor.
Stops or water main closed.
Bad sensor to solenoid connection.
Debris or scale in
solenoid assembly.
Remove solenoid, pull out plunger
and spring, and clean with scale
remover solution or pressurized air.
Debris or scale in diaphragm.
Remove diaphragm and clean
Sensor flashes once
when user’s hands are
within range.
Remove strainer and clean.
CONDITION:
FALSE TRIGGERING;
WATER FLOWS CONTINUOUSLY
Indicators
Probable Cause
Solution
Remove diaphragm and clean.
Sensor flashes when user’s
hands are within range.
Diaphragm is defective or torn.
Sensor is dirty or covered.
Clean or uncover sensor and
wait 30 seconds.
Decrease range and wait 30 seconds.
Sensor does not flash when
users hands are within range.
Range too long or highly
reflective surface, sunlight, bright
lights etc. are triggering sensor.
Eliminate cause of reflection or
correct lighting problem.
CONDITION:
WATER FLOWS
CONTINUOUSLY BUT STOPS
WHEN HANDS ARE WITHIN RANGE
Indicators
Probable Cause
Solution
Water runs continuously when
sensor not activated. Sensor
flashes when hands are within
range and water shuts off.
Solenoid polarity crossed.
Disconnect solenoid and
reverse polarity.
Battery completely used up.
Replace transformer.
Open stops or water main.
Ensure wires make proper contact.
Debris or scale in strainer.
Replace diaphragm.
Debris or scale in diaphragm
Part #: 9927-141-001
Page 20 of 28
Date: 03/07/19
