Product Manual

QT/QTS Series Quincy Compressor

50161-108, January 2013 41 3501 Wismann Lane, Quincy Ill. - 62305-3116

SECTION 6 TROUBLESHOOTING

Trouble Probable Cause

Low discharge pressure •Restricted inlet

•Defective compressor valves or valve unloading mechanism

•Leaks in the compressed air distribution system at ﬁttings, connections,

etc.

•Unloader pilot valve defective or set wrong

•Pressure switch defective or set wrong

•Drive belt slipping

•Incorrect speed

•Worn piston rings or loose piston

•Leaking head gasket

•Drain valve open

•Defective pressure gauge

•Pressure relief valve leaking

•Clogged intercooler

•Compressor incorrectly sized for the alti tude it is operating at

•Piston rings not seated; allow 100 hours at full pressure

Water in the crankcase •Compressor does not run long enough to get hot and vaporize the liquids

(lubricant appears milky) squeezed out of the air during compression (compressor may be too large

for application)

•Incorrect or inferior grade of lubricant

•System pressure leaking back through dis charge valve

Rusty valves •Compressor operated too infrequently

and/or cylin ders •Compressor does not run long enough to get hot and vaporize the liquids

squeezed out of the air during compression (compressor may be too large

for application)

•Compressor not properly prepared for stor age

•Discharge line from compressor head is pointed upward allowing con

densation to drain back at shutdown

Excessive vibration •Incorrect speed

•Compressor valves not functioning prop erly

•Loose pulley/sheave

•Compressor, motor or engine not secured tightly, or tightened into a

bind

•Foundation or frame inadequate

•Piping inadequately supported or tightened into a bind

•Excessive discharge pressure

•Compressor feet may need to be leveled with shims