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Problem
Probable Cause
Solution
Regulator Will Not
Provide Pressure
Control
Regulator seat is restricted
Locate and remove stoppage, install strainer
Pressure adjusting stem is set at a point so
high that suction pressure never reaches
the setpoint
Re-adjust the regulator
Strainer clogged at the regulator inlet
Locate and remove stoppage
MOPD exceeded across the solenoid or loss
of source voltage
Replace solenoid or troubleshoot the
electrical problem
Solenoid coil burned out
Replace coil
Wrong type of distributor for hot gas bypass
to the evaporator
Install proper venture-flo type distributor for
low pressure drop
Regulator Fails
To Close
Dirt under seat of regulator
Locate and remove stoppage, install strainer
or filter drier
Diaphragm failure (leakage around the
adjusting stem)
Replace defective parts
Pressure adjusting stem is set at a point so
high that suction never reaches the setpoint Re-adjust the regulator
Blocked external equalizer passage
Locate and remove stoppage, install strainer
Worn or eroded regulator seat
Replace defective part
Table 13.4: Variable Speed Head Pressure Control, Cont.
PR Series Installation, Operation, and Maintenance Manual
