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Electrical Maintenance
86
Figure 12: RPM+ and RPM- Wires
3. Place the unit in Continuous Run. Run the unit
on low speed and high speed. Check the AC
voltage output across the sensor terminals.
Use a meter with a high ohms per volt internal
resistance. A Simpson 260, Fluke digital or
any good VOM will work. However, an
automotive type meter may not give an
accurate reading because the meter may load
the circuit heavily and cause the voltage level
to appear lower than it actually is.
a. The output voltage should be 1.0 to
2.0 Vac on low speed.
b. The output voltage should be 2.0 to
2.5 Vac on high speed.
NOTE: If the voltage is slightly off, the
voltage may be increased by turning the
sensor in more, and the voltage may be
lowered by turning the sensor out more.
4. Reconnect RPM+ and RPM- wires on RPM
sensor.
If the RPM sensor passes the above test, the
sensor may be considered good.
If the unit is not available, an alternate less
reliable test may be performed as follows:
Disconnect the sensor from all wires, and measure
the resistance across the terminals and from each
terminal to the aluminum case. The resistance
should be 250 to 300 ohms across the terminals,
and there should be no continuity from each
terminal to the case.
Glow Plugs
Glow plugs heat the combustion chamber to aid in
quick starting. The glow plugs are energized when
the microprocessor initiates unit start-up. A
defective glow plug (burned out) can be detected
by placing an external ammeter in series with the
plugs. Normal current draw is approximately
21 to 25 amps when preheating. A current draw of
21 to 25 amps means all three glow plugs are
working. If the current draw is less than 21 amps
on Preheat, at least one glow plug is bad.
To isolate an open circuit glow plug, remove the
jumper bar and test each glow plug individually
with an ohmmeter or a jumper wire and ammeter.
Each glow plug should have a resistance of
approximately 1.5 ohms or a current draw of
about 8 amps.
With an external ammeter connected in series, a
shorted glow plug will show excessive current
flow (more than 12 amps) when the Preheat is
initiated. When fuse F6 is blown, check each plug.
1.
Ohmmeter
2.
1.5 Ohms
3.
Remove Bar
Figure 13: Glow Plug Test
Summary of Contents for 914970
Page 3: ...3...
Page 10: ...Table of Contents 10...
Page 40: ...Operating Instructions 40...
Page 82: ...Electronic Controls 82...
Page 92: ...Electrical Maintenance 92...
Page 124: ...Refrigeration Maintenance 124...
Page 140: ...Hilliard Clutch Maintenance 140...
Page 160: ...Refrigeration Diagrams 160...
Page 163: ...Index 163 W wiring 85 wiring diagrams 165...
Page 164: ...Index 164...
Page 166: ...Wiring and Schematic Diagrams Index 166...
Page 167: ...167 Cab Control RD Wiring Diagram...
Page 168: ...168 RD w o Thermostat Cab Control Schematic...
Page 169: ...169 RD Cab Box Wiring Diagram...
Page 170: ...170 RD Cab Control w Thermostat Schematic Diagram...
Page 171: ...171 RD 50 STD 3 Phase Wiring Diagram Page 1 of 2...
Page 172: ...172 RD 50 STD 3 Phase Wiring Diagram Page 2 of 2...
Page 173: ...173 RD 50 STD 3 Phase Schematic Diagram Page 1 of 2...
Page 174: ...174 RD 50 STD 3 Phase Schematic Diagram Page 2 of 2...
Page 175: ...175 RD 30 STD Wiring Diagram Page 1 of 2...
Page 176: ...176 RD 30 STD Wiring Diagram Page 2 of 2...
Page 177: ...177 RD 30 STD Schematic Diagram Page 1 of 2...
Page 178: ...178 RD 30 STD Schematic Diagram Page 2 of 2...
Page 179: ...179 RD 30 C S Wiring Diagram Page 1 of 2...
Page 180: ...180 RD 30 C S Wiring Diagram Page 2 of 2...
Page 181: ...181 RD w CYCLE SENTRY Schematic Diagram Page 1 of 2...
Page 182: ...182 RD w CYCLE SENTRY Schematic Diagram Page 2 of 2...
Page 183: ...183 RD 50 C S 3 Phase Wiring Diagram Page 1 of 2...
Page 184: ...184 RD 50 C S 3 Phase Wiring Diagram Page 2 of 2...
Page 185: ...185 RD w CYCLE SENTRY Schematic Diagram Page 1 of 2...
Page 186: ...186 RD w CYCLE SENTRY Schematic Diagram Page 2 of 2...