Carrier VECTOR 6500 Operation & Service Manual page 162

Alarm
Steps
NO.
38 CHECK HIGH SPEED RPM
•
TRIGGER–ON: The microprocessor is set for high engine speed operation, and engine speed is:
less than 1650 rpm, or greater than 1950 rpm for more than 60 seconds (120 seconds when the
microprocessor calls for a change from low to high speed, or when unit first starts).
•
UNIT CONTROL:
•
RESET CONDITION: Auto Reset if microprocessor is set for high speed operation and the signal is
between 1650 and 1950 for 60 seconds or change unit to standby Operation 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.
a. Check ENSCU 16.
b. Check circuit from ENSCU 16 to
microprocessor connection MPQC3.
3 Check Fuel/Speed Actuator (FSA) plunger
Check plunger on fuel/speed actuator. Must move in and out freely.
4 Check FSA Harness
a. Inspect harness & control box
connector pins & terminals. (See
wiring schematic Section 10.)
b. Check resistance of fuel/speed
actuator.
5 Force High Speed Operation
a. Adjust set point to at least 20
degrees away from compartment
temperature. If the unit does not
immediately go into High Speed,
ensure the Silent Mode Functional
Parameter is set to OFF and/or the
applicable
Configuration is set to OFF. (Reset
following testing.)
b. Check operation of Speed Relay
LED.
c. Check voltage on the engine
speed control unit (ENSCU, pin 16.)
Additional steps on the next page.
Alarm/Cause
Engine Operation: alarm only.
Standby Operation: this alarm will not activate in standby Operation.
matches the model
High Speed Delay
7−29
Corrective Action
Enter the correct number in Configurations. (Refer to
Section 5.2.1.)
12 VDC between ENSCU 16 and ENSCU19.
Must be 12 VDC at MPQC3 and ENSCU16.
Spring tension must hold rod firmly extended and in
place.
No physical damage to harness.
No damage, moisture, or corrosion in connectors.
Refer to Section 2.12 for correct electrical values.
The microprocessor will call for High Speed opera-
tion.
LED 27 must be ON. (If LED 27 is not on, the micro-
processor is not calling for High Speed operation.
Check Speed Overrides in Section 4.8.3 for more
information.)
Must be 12-14 VDC
62-11389