Carrier VECTOR 6500 Operation & Service Manual page 161

Alarm
Steps
NO.
37 CHECK LOW SPEED RPM
•
TRIGGER–ON: The microprocessor is set for low engine speed operation, and engine speed is: less
than 1200 rpm, or greater than 1500 rpm for more than 60 seconds (120 seconds when the
microprocessor calls for a change from high to low speed, or when unit first starts).
•
UNIT CONTROL: Alarm Only
•
RESET CONDITION: Auto Reset if microprocessor is set for low engine speed operation and
signal is: Between 1200 to 1500 RPM for 60 seconds, or Alarm may be manually reset via keypad
or by turning the unit off, then back on again.
NOTE: Follow the steps below until a problem is found. Once a repair or correction has been made, the active
alarm should clear itself (see reset condition above). Operate the unit through the appropriate modes to see if
any active alarm occurs. Continue with the steps below as necessary.
1 Check Model Number
Verify that the model number on the
nameplate
number shown in the microprocessor
Unit Data.
2 Check For Proper Voltage To The Engine Speed Control Unit (ENSCU) Pin 16. Check
For Proper Voltage With Unit Running.
Check ENSCU 16.
3 Check Fuel/Speed Actuator (FSA)
Check fuel/speed actuator.
4 Force Low Speed operation
a. Using Functional Parameters, set
the Low Speed Start Up Delay to 10
minutes.
b. Check operation of Speed Relay
LED.
c.Check voltage at engine speed
control unit (ENSCU) pin 16.
5 Check Engine RPM
a. Check actual engine RPM using
hand held tachometer.
b. Compare actual RPM with those
shown on display.
6 Check Engine Air–Intake System
a. Check air cleaner indicator.
b. Inspect air intake system.
7 Check Engine Fuel System
a. Check fuel tank level.
b
c
d
8 Check Engine Exhaust System
Inspect the exhaust system.
62-11389
Alarm/Cause
matches the
Check fuel lines.
Check fuel screen.
Check fuel filters.
Enter the correct number in Configurations. (Refer to
Section 5.2.1.)
model
0 VDC between ENSCU 16 and ENSCU 19 (GND.)
Plunger must move in and out freely. Refer to Engine
Manual.
Unit will run in low speed. RPM must be within range
shown above for each specific model. Refer to
Speed Control System Diagnotics, Section 9.5. Clear
all fault codes before continuing.
LED 27 must be OFF.
Must be 0 VDC.
Refer to Table 2-1.
Both readings within ± 50 RPM.
Flag must not be visible.
Hoses & tubes in good condition.
No kinks or restrictions.
Must have enough fuel to run engine.
Connections are tight and not leaking.
No kinks or sharp bends in the lines.
Fuel screen is located in the inlet fitting to the lift
pump. Screen must be clean.
Fuel filters must be clean and allow full flow of fuel
through them.
Must be clear and unobstructed.
7−28
Corrective Action