Motor Diagnostics
332697C
27
Motor Diagnostics
A20, A30, and A45
Motor Diagnostics reveal a damaged motor or if motor
brushes are shorter than 1/4 in. (6.4 mm) replace the
motor using
Motor Kit
. See
List of Kits
, page 30.
Setup
1. Unplug power cord and
Relieve Pressure.
See
Pressure Relief Procedure,
page 13.
2. Remove enclosure and disconnect two motor leads.
See
Wiring Diagram
3. Remove motor fan cover by gently prying up on
retention tabs on sides of motor. Motor shaft should
spin easily when turning fan. If motor shaft does not
turn easily, there is a problem with pump, gears, or
motor. See
Basic
Troubleshooting
, page 15.
4. Inspect motor windings for evidence of overheating.
If windings appear burnt and motor smells, replace
motor.
5. Use ohmmeter to measure resistance across two
motor leads. Resistance of motor should fall within
range of 4.0 to 10.0 ohms. If motor falls outside
resistance range or is open circuit, replace motor.
6. Use ohmmeter to measure resistance of motor
leads to motor laminations. If resistance is not open
circuit, replace motor.
7. Inspect length of both brushes by looking at brush
torsion spring. If spring is not bottomed out in slot for
brush spring, brush length is acceptable. If brushes
are worn out, replace motor.
A60
Check for electrical continuity in motor armature,
windings and brush as follows:
If Motor Diagnostics reveal a damaged motor or if motor
brushes are shorter than 1/4 in. (6.4 mm) or if the motor
shaft cannot turn, replace the motor using
Motor Kit
.
See
List of Kits
, page 30.
Setup
1.
Relieve Pressure.
See
Pressure Relief Proce-
dure,
page
2. Unplug electric cord.
3. Remove enclosure and disconnect motor leads from
control card.
4. Remove fan brace.
5. Remove four screws and front cover.
6. Remove yoke and guide rods.
7. Remove gear.
Armature Short Circuit Spin Test
Quickly turn motor fan by hand. There should not be
electrical shorts and fan should coast two or three
revolutions before stopping. If fan does not spin freely,
armature is shorted. Replace motor using
Motor Kit
.
See
List of Kits
, page 30.
Armature, Brushes and Motor Wiring
Open Circuit Test (Continuity)
1. Connect a test lead to each of the red and black
motor leads.
2. Turn motor fan by hand, about two revolutions per
second.
3. If there is an uneven resistance or no resistance
measured across the test leads, replace motor
using
Motor Kit
. See
List of Kits
, page 30.
