U0627: Lost Communication With A/C Refrigerant Temperature Sensor A

What it means

A control module has stopped receiving expected network messages from A/C refrigerant temperature sensor A. The effect on A/C operation depends on the vehicle's system design.

How it works

A/C refrigerant temperature sensor A sends temperature information over the vehicle network so the A/C controls can manage system operation. U0627 sets when a receiving module no longer gets the expected messages from sensor A. A/C operation may be limited if the system cannot verify refrigerant temperature.

Common causes

Most likely first.

1. Bus wiring open or shorted
2. Module without power or ground
3. Module failed

Symptoms

• A/C may not operate as intended
• Warning light or message related to the A/C system

How to diagnose it

1. Scan all modules and save available event data to check whether the missing sensor A messages began with other network faults.
2. Check A/C live data for refrigerant temperature sensor A and see whether its value is missing while other temperature readings remain available.
3. Inspect sensor A's connector and nearby network wiring for damage, corrosion, loose pins, or moisture.
4. Check the sensor module's power and ground against the manufacturer's specification.
5. Test the communication wiring to temperature sensor A for opens or shorts using the vehicle wiring diagram and manufacturer's procedure.

Common fixes

• Clean and secure sensor A's connector or repair damaged wiring.
• Restore the sensor module's power or ground.
• Repair an open or short in the bus wiring serving temperature sensor A.
• Replace the sensor module after confirming its power, ground, and network wiring are sound.

Can I keep driving?

You can generally drive the vehicle, but A/C performance or demisting may be reduced if the system disables cooling. Use another safe way to keep the windows clear if needed.