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Series 830/840/860 Instruction Manual Chapter 5 Troubleshooting
IM-83/84/86-H 5-3
Flow Controllers with Motor-operated Rotary Valves
Problem
Possible Cause
Solution
Valve “hunts” back and forth
continuously
Pressure differential too great
Motor coupling set screws loose
Valve motor failure
Reduce pressure
Tighten set screws
Replace motor
Valve rotates continuously
Limit switch out of adjustment or bro-
ken
Microprocessor failed
Adjust or replace switch
Replace microprocessor
Valve does not rotate
Contaminant blocking valve
Motor fuse blown
Remove blockage
Replace 1 amp fast blow fuse on
motor valve board
Flow reading is erratic
Inlet filter screen clogged
Clean or replace screen
Reads full scale with no flow or
with valve shut
Defective sensor
Q1 shorted
U10 failed
Return to factory for replacement
Replace with same type part
Replace with same type part
Flow does not match set point
within specifications
Insufficient pressure differential
Increase pressure or reduce set
point