Preventive Maintenance Checks and Services continued
Section IV. TROUBLESHOOTING
The electric motor is made up of electrical and mechanical
4-10. GENERAL. This section contains troubleshooting
components. The main mechanical components to go bad
procedures to be performed by organizational maintenance.
4-11. ELECTRIC. Problems in the motor control cir-
cuitry will usually cause the motor to stop running.
Other malfunctions are usually due to problems with the
Note that there has to be current through the coil for con-
tacts E1, E2 and E3 to close. This means that the motor
4-12. COMPRESSOR. The compressor drive is a fairly
won't run if the coil circuit is bad even though the rest of
simple system. The main problems are improper belt ten-
the circuit is good.
sion, bad alignment and loose parts.
Overload conditions will cause the overload relay contact to
open. Overloading may be caused by shorts in the motor or
The intake and exhaust valves are the most critical parts of
by a blockage in the compressor. Overload conditions must
the compressor. Loss of pumping efficiency can most often
be removed before the compressor can be put back in oper-
be traced back to the valves.
ation. Otherwise, the relay will just open up again.
However, problems with getting enough air aren't always
Once overload conditions have been eliminated, the RESET
caused by the compressor. Leaky fittings or an improperly
button on the motor control box can be pushed to start
the compressor back up.
adjusted pressure switch may also be at fault.