Troubleshooting - Quincy QGB Series Instruction Manual

Section V - Integrated Dryer (option)
Hot Gas Bypass Valve
Integrated air dryers come equipped with
modulating hot gas bypass valves. This
valve maintains the refrigerant suction
pressure in varying load conditions.
The dryer will run from no load to full
load conditions without freeze-up. The
operation of this valve is automatic. If
the valve needs adjustment, turn the
adjusting stem clockwise to raise the
suction pressure, and counterclockwise to
lower the suction pressure. This adjustment
should be made under a no-load
condition. When the adjustment is made,
turn one quarter of a turn at a time, and
wait 3 to 5 minutes between adjustments.
Once the adjustment is complete, secure
the adjusting stem with the locknut that is
provided. Careful adjustment of this valve
is necessary for normal operation of the
air dryer. Hot gas bypass valve adjustment
may be made by maintenance personnel.

Troubleshooting

notiCe!
The alarm indication light (red) signifies
the refrigerant compressor is not
running. The reasons can be:
•Low suction pressure
•High discharge pressure
•Electrical problems
•Loss of refrigerant
•Dirty condenser
•Leaking evaporator, etc.
Refer to the Troubleshooting section for
problem analysis and remedy. Call the
factory if further assistance is required.
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Hot Gas Bypass Valve Adjustments
The following conditions can cause
abnormal operation or malfunction of the
air dryer:
• High inlet air temperatures
• Dirty condenser
• Low ambient temperatures
• Malfunctioning automatic drains at
aftercooler, or dryer
• Refrigerant overcharge
• Leaky evaporator
• Electrical power supply more than
±10% of the rated voltage
• Low inlet air pressures
• High ambient temperatures
• Compressed air flow greater than rated
capacity
• Undersized fuses
• Refrigerant undercharge
If any of these symptoms are noticed, refer
to Section VIII - Troubleshooting.
Quincy Compressor-QGB
™