Carrier VECTOR 1550 Series - Check Eng Coolant Sensor (Enct)

62-61753-21
7-67
Alarm
NO.
Steps
ALARM / CAUSE
CORRECTIVE ACTION
129 CHECK ENG COOLANT SENSOR (ENCT)
 TRIGGER-ON: Sensor is not within the range of -50 to +130°C (-58 to +266°F).
 UNIT CONTROL: Engine operation: Alarm Only.
Standby operation: This alarm does not activate in standby.
 RESET CONDITION: Auto Reset 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 (refer to 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 Sensor Wiring
a. Inspect sensor & connector pins &
terminals. (See wiring schematic
Section 10.)
No physical damage to sensor.
No damaged or corroded pins in plug.
b. Energize sensor circuit.
Check for voltage at the sensor
plug between pins A (+) and B
(ground).
Refer to Note 2 Page 7-2.
Voltage should be approximately 12 VDC.
2
Check Sensor
a. Check Sensor resistance. (Refer to
Note 3 page 7-2.)
Refer to Section 8.7.7 for complete table of tempera-
tures and resistance values.
3
Check Circuits With Another Sensor
a. Substitute known good sensor and
clear alarm. Start unit and run for
30 seconds.
b. Check to see if alarm re-occurs.
Alarm should not come on. (Install new sensor if nec-
essary)