Could a failing Coolant Temperature Sensor cause the CARRIER COMFORTPRO 15 to have symptom: Starts Then Shuts Off?

The sensor uses a thermistor to provide a resistance-based temperature reading to the Engine Control Unit (ECU). If the sensor fails or the connection is compromised by engine vibration, the ECU detects an out-of-range value and interprets it as a critical overheat condition. To prevent engine seizure, the safety logic immediately cuts power to the fuel solenoid, causing the engine to shut down shortly after startup.

Could a failing Alternator/Water Pump V-Belt cause the CARRIER COMFORTPRO 15 to have symptom: Starts Then Shuts Off?

This belt drives both the water pump and the DC alternator; if it snaps or slips significantly, the alternator fails to send a charging signal to the controller. The APU's monitoring system requires a confirmed DC voltage rise to verify the engine is running and capable of self-sustenance. Without this feedback signal, the system triggers a 'Charging System Failure' shutdown within approximately 15-20 seconds.

Could a failing Oil Pressure Switch cause the CARRIER COMFORTPRO 15 to have symptom: Starts Then Shuts Off?

This is a diaphragm-actuated safety switch that closes once the engine reaches a specific PSI of lubrication pressure. If the switch's internal contacts are oxidized or the diaphragm is fouled, the 'low oil pressure' signal remains active even if pressure is physically present. The controller allows for a short grace period during cranking but will abort the run sequence if the switch does not actuate within seconds of ignition.

What is the most likely root cause for a CARRIER COMFORTPRO 15 with symptom: Starts Then Shuts Off?

The sensor uses a thermistor to provide a resistance-based temperature reading to the Engine Control Unit (ECU). If the sensor fails or the connection is compromised by engine vibration, the ECU detects an out-of-range value and interprets it as a critical overheat condition. To prevent engine seizure, the safety logic immediately cuts power to the fuel solenoid, causing the engine to shut down shortly after startup.

CARRIER COMFORTPRO 15 Starts Then Shuts Off

CONF	DIAGNOSIS	ACTION
91% CONF	Coolant Temperature Sensor The sensor uses a thermistor to provide a resistance-based temperature reading to the Engine Control Unit (ECU). If the sensor fails or the connection is compromised by engine vibration, the ECU detects an out-of-range value and interprets it as a critical overheat condition. To prevent engine seizure, the safety logic immediately cuts power to the fuel solenoid, causing the engine to shut down shortly after startup.	VIEW ON AMAZON #CommissionsEarned
5% CONF	Alternator/Water Pump V-Belt This belt drives both the water pump and the DC alternator; if it snaps or slips significantly, the alternator fails to send a charging signal to the controller. The APU's monitoring system requires a confirmed DC voltage rise to verify the engine is running and capable of self-sustenance. Without this feedback signal, the system triggers a 'Charging System Failure' shutdown within approximately 15-20 seconds.	VIEW ON AMAZON #CommissionsEarned
4% CONF	Oil Pressure Switch This is a diaphragm-actuated safety switch that closes once the engine reaches a specific PSI of lubrication pressure. If the switch's internal contacts are oxidized or the diaphragm is fouled, the 'low oil pressure' signal remains active even if pressure is physically present. The controller allows for a short grace period during cranking but will abort the run sequence if the switch does not actuate within seconds of ignition.	VIEW ON AMAZON #CommissionsEarned

DIY Repair Guide

Watch exactly how to replace the Coolant Temperature Sensor.

// NOTICE: This report is generated by an Agentic AI Engineer utilizing probabilistic modeling.

PartSniper is an automated parts recommender service. AI-generated results may not be correct. This data is not a substitute for professional engineering advice or manual inspection. Always verify part compatibility and disconnect power before any repair. PartSniper is not liable for inaccuracies, injury, or damage.

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CARRIER COMFORTPRO 15 Starts Then Shuts Off

DIY Repair Guide