Craftsman 921.16578 Owner's Manual page 12

Note: Troubleshooting problems may have similar causes and solutions.
PROBLEM POSSIBLE CAUSE SOLUTION
Excessive current draw Low voltage/motor overload Check that power supply is adequate and that compressor is on a
trips circuit breaker or dedicated circuit.
motor reset switch Drive belt tension too tight Readjust belt tension.
Restricted air passages Inspect and replace transfer tubes or the check valve, (see "To replace
or clean check valve" in the maintenance section).
Compressor stalls Low voltage to motor Furnish adequate power.
Bad check valve Replace the check valve (see "To replace or clean check valve" in the
maintenance section).
Seized pump Contact a Sears or other qualified service center.
Low discharge pressure Air leaks Tighten or replace leaking fittings or connections. Do not overtighten.
Leaking valves Contact a Sears or other qualified service center.
Restricted air intake Clean or replace air filter element(s).
Blown gaskets Contact a Sears or other qualified service center.
Worn piston rings or cylinder Contact a Sears or other qualified service center.
Compressor pump Loose motor pulley or pump Retighten pulley and flywheel. Check alignment.
knocking flywheel
Low oil level in pump crankcase Keep oil at proper level at all times.
Excess carbon on valves or top Contact a Sears or other qualified service center.
of piston
Oil in discharge air Worn piston rings or cylinder Contact a Sears or other qualified service center.
Restricted air intake Clean or replace the air filter element(s).
Oil level too high Reduce to proper level.
Overheating Poor ventilation Relocate compressor to an area with cool, dry, welt circulated air, at
least 12 in. from nearest wall.
Dirty cooling surfaces Clean all cooling surfaces thoroughly.
Restricted air passages Inspect and replace transfer tubes or the check valve, (see "To replace
or clean check valve" in the maintenance section).
Excessive belt wear Pulley out of alignment Realign pulley with compressor flywheel.
Improper belt tension Readjust.
Pulley wobbles Replace the pulley and check for a damaged crankshaft or flywheel.
Compressor won't start in Too much back pressure in tank Open petcock when starting motor.
cold temperatures 40W oil in crankcase Use synthetic blend, non-detergent air compressor oil.
Compressor too cold Move compressor to a warmer location.
Air leaking through Dirty or defective check valve. Replace or clean the check valve (see "To replace or clean check
bleeder valve after valve" in the maintenance section).
compressor shuts off
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