Craftsman 921.166420 - Manual (Page 9)

Troubleshooting Guide
A WARNING
The air compressor should be turned off and unplugged from the power source before any maintenance
is performed as well as the air bled from the tank and the unit allowed time to cool. Personal injuries
could occur from moving parts, electrical sources, compressed air, or hot surfaces.
PROBLEM POSSIBLE CORRECTION
Air leaks at the check valve or at the pres­
sure relief valve. A defective check valve results in a constant air leak at the pressure relief
valve when there is pressure in the tank and the compressor is shut off.
Drain the tank, then remove and clean or replace the check valve.
Air leaks between head and cylinder. Be sure of proper torque on head bolts. If leak remains, contact a service
technician.
Air leak from safety valve. Operate the safety valve manually by pulling on the ring. If the valve con­
tinues to leak when in the closed position, it should be replaced.
Pressure reading on the regulated
pressure gauge drops when an accessory
is used.
If there is an excessive amount of pressure drop when the accessory is
used, replace the regulator.
NOTE
Adjust the regulated pressure under flow conditions (while accessory is
being used). It is normal for the gauge to show minimal pressure loss dur­
ing initial use of the tool.
Excessive tank pressure. Move the Auto-On/Off switch to the Off position. If the unit doesn’t shut
off, unplug it from the power source and contact a service technician.
Motor will not start. Make sure power cord is plugged in and the switch is on. Inspect for the
proper size fuse in your circuit box. If the fuse was tripped, reset it and
restart the unit. If repeated tripping occurs, replace the check valve or
contact a service technician.
Thermal overload protector cuts
out repeatedly. 1 . Lack of ventilation, room temperature too high. Move to cooler
environment.
2. Excessive air usage, compressor too small for this application. Lower
rate of consumption.
Excessive moisture in the discharge air. Remove the water in the tank by draining after each use. High humidity
environments will cause excessive condensation. Utilize water filters on
your air line.
NOTE
Water condensation is not caused by compressor malfunction. Be sure
the compressor’s air output is greater than your tool’s air consumption
rate.
Air leaks from the tank body or tank welds. Never drill into, weld or otherwise modify the air tank or it will weaken.
The tank can rupture or explode. Compressor cannot be repaired.
Discontinue use of the air compressor.