Faulty engine coolant temperature (ECT) sensor sending an incorrect high-temperature signal; Low engine coolant level or trapped air in the cooling system causing localized overheating; A failing thermostat that restricts coolant flow and raises ECT readings; Wiring damage or corrosion in the ECT sensor circuit (open, short, or high resistance); A/C system overcharge or restriction causing the compressor to overheat and raise underhood temperatures; Radiator fan(s) not operating correctly, leading to inadequate airflow and elevated coolant temperature; PCM calibration issue or internal fault in the A/C overtemperature protection logic

DTC codes / Chrysler codes / P1536

P1536 · ChryslerA/C System ECT Overtemperature

Q: What does code P1536 mean?

A/C System ECT Overtemperature. P1536 on Chrysler vehicles indicates the powertrain control module (PCM) has detected an overtemperature condition in the air conditioning (A/C) system's engine coolant temperature (ECT) circuit, meaning the A/C compressor may be overheating or the ECT sensor is reporting an abnormally high coolant temperature that affects A/C operation. The PCM monitors the ECT signal and disables the A/C compressor clutch to protect the system when the coolant temperature exceeds a calibrated threshold.

P1536 on Chrysler vehicles indicates the powertrain control module (PCM) has detected an overtemperature condition in the air conditioning (A/C) system's engine coolant temperature (ECT) circuit, meaning the A/C compressor may be overheating or the ECT sensor is reporting an abnormally high coolant temperature that affects A/C operation. The PCM monitors the ECT signal and disables the A/C compressor clutch to protect the system when the coolant temperature exceeds a calibrated threshold.

SystemPowertrain

Code typeChrysler specific

SeverityMedium

Fix difficultyIntermediate

AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

The air conditioning may stop blowing cold air intermittently or completely
The A/C compressor clutch may not engage when the engine is hot
The check engine light (malfunction indicator lamp) is illuminated
Engine temperature gauge may read higher than normal or fluctuate
Often no symptoms besides the warning light, especially in cooler ambient temperatures
Possible reduced engine performance or cooling fan running constantly

Common causes, most likely first

Faulty engine coolant temperature (ECT) sensor sending an incorrect high-temperature signal
Low engine coolant level or trapped air in the cooling system causing localized overheating
A failing thermostat that restricts coolant flow and raises ECT readings
Wiring damage or corrosion in the ECT sensor circuit (open, short, or high resistance)
A/C system overcharge or restriction causing the compressor to overheat and raise underhood temperatures
Radiator fan(s) not operating correctly, leading to inadequate airflow and elevated coolant temperature
PCM calibration issue or internal fault in the A/C overtemperature protection logic

How to diagnose and fix it

Verify coolant level and condition; top off or bleed the cooling system if low or air is present
Use a scan tool to read live ECT sensor data and compare it to actual coolant temperature with an infrared thermometer
Inspect the ECT sensor and its connector for corrosion, loose pins, or damaged wiring; repair as needed
Test the thermostat for proper opening temperature and replace if it sticks closed or opens late
Check radiator fan operation by commanding the fans on with the scan tool and observing operation
Perform an A/C system performance test to check for overcharge or restriction; recover, evacuate, and recharge if necessary
If all else checks out, reflash or replace the PCM only after confirming the overtemperature condition is real and not a false signal

Don't overlook the cooling system basics

A marginal coolant level or a small air pocket can cause localized hot spots that trigger P1536 without the temperature gauge showing an obvious overheat.
The ECT sensor on Chrysler engines often shares a ground with other sensors; a poor ground can skew the ECT reading and set this code even when actual coolant temperature is normal.
A sticking thermostat may not set a thermostat-specific code but can cause P1536 by raising coolant temperature just enough to trigger the A/C overtemperature protection.
Aftermarket A/C refrigerant that is overcharged can raise compressor head pressure and underhood temperature, leading to P1536 without any electrical fault.
The PCM may disable the A/C compressor as a protective measure, so a complaint of 'A/C not working' can be the first sign of P1536 even before the check engine light comes on.

Can I keep driving with P1536?

You can usually drive the vehicle with P1536, but avoid using the A/C and monitor the engine temperature gauge closely; if the gauge climbs above normal or you notice coolant loss, stop and address the cooling system before continuing.

Tools that help

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Guidance is general and written for Chrysler vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.