52 Preliminary
PTS 916 Cd
Compressor capacity or
pressure below normal
Safety valve or relief valve(s) leaking. Remove and inspect safety valve or relief
valve(s). Replace valve(s) if not airtight after
reinstallation.
Unloading valve leaking. Remove and inspect unloading valve. Replace
valve, if necessary.
Pipe connections leaking.
Check connections and repair if necessary.
Air pressure rises above
maximum and causes safety
valve to blow off
Working pressure setpoint incorrect. Adjust setting.
Air intake throttle valve does not close for some
reason.
Check position throttle valve.
Disconnect loading solenoid valve from throttle
valve housing and connect independent
compressed-air line to throttle valve housing.
Repeatedly admit air and listen for opening and
closing sound of throttle valve. If sound is not
evident, remove unloader valve assembly,
dismantle and inspect. Replace parts where
necessary.
Unloading valve malfunctioning. Remove and inspect unloading valve and blow-
off silencers.
Compressor overheating Insufficient compressor cooling. Move unit away from walls; when banked with
other units, leave space between them.
Oil cooler clogged externally. Clean oil cooler.
Oil cooler clogged internally. Consult Atlas Copco.
Compressor oil filter clogged. Replace oil filter.
Compressor oil level too low. Before checking compressor oil level, wait
approx. 10 minutes after unit has stopped.
Add correct oil, if necessary. Never overfill.
Fan blade broken or fan drive defective. Check and correct, if necessary.
Working pressure too high. Adjust setting.
Pressure ratio over compressor element(s) too
high.
Consult Atlas Copco.
Electric blow-off valve malfunctioning. Check interstage pressure. Check functioning of
loading solenoid valve. Replace diaphragm of
blow-off valve if necessary.
By-pass valve of oil cooler remains stuck in open
position.
Remove bypass valve, clean and inspect.
Engine running but
compressor does not load
when ‘Load’ button is pressed
Loading solenoid valve inoperative. Check loading solenoid valve and electric wiring.
Replace valve, if necessary.
Diaphragm of unloader piston perforated or
throttle valve remains closed for some reason.
Remove unloader piston cover and inspect
rolling diaphragm. If in order, check piston for
free axial movement by hand. If jammed, remove
throttle valve housing, dismantle and replace
defective parts.
Control panel ‘Load’ button inoperative. Consult Atlas Copco.
Symptom Possible cause Corrective action
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