Quincy Compressor 50093-103 - Manual (Page 66)

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INLET VALVE NOT OPENING OR CLOSING IN RELATION TO SYSTEM DEMAND
PROBABLE CAUSE CORRECTION
Improper setting of vacuum pressure
switch or faulty switch Adjust vacuum pressure switch to proper setting or replace
switch, if faulty.
Improper functioning of inlet valve
piston Check piston and cylinder bore. Repair or replace as
needed.
Jammed air inlet valve assembly Check air inlet valve bushing and shaft. Check piston and
cylinder bore. Repair or replace as needed.
Faulty differential pilot valve Repair or replace as necessary.
Broken spring in air inlet valve Replace spring.
Faulty solenoid valve Repair or replace as necessary.
Faulty shuttle valve Repair or replace as necessary.
Loose wiring connections at solenoid
valve/pressure switch Check and tighten wiring terminals.
Incorrect vacuum switch setting Adjust pressure switch to proper setting.
Faulty vacuum switch Replace switch.
Leaks in control lines Check all control line fittings and tubing.
VACUUM PUMP DOES NOT LOAD WHEN VACUUM LINE PRESSURE RISES
PROBABLE CAUSE CORRECTION
Faulty vacuum pressure switch Repair or replace as necessary.
Loose wiring connection Check and tighten wiring terminals.
Jammed air inlet valve assembly Check and repair air inlet valve.
Faulty solenoid Repair or replace as necessary.
Faulty timer Check and replace timer.
Faulty differential pilot valve Orifice plugged. Clean or replace as necessary