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A/C works intermittently or cuts out during driving

Q: What are the symptoms of A/C works intermittently or cuts out during driving in Chevrolet Sierra?

Air conditioning works intermittently. Vibrations or humming after turning on A/C

Q: How to fix A/C works intermittently or cuts out during driving in Chevrolet Sierra?

Repair of wire insulation and changing the harness routing (conduit insulation). Look for a chafing spot directly at the compressor plug or along the engine block. The vibrations in these models are deadly to thin control cables.

in Chevrolet Sierra (2007-2013)

Symptoms

Air conditioning works intermittently
Vibrations or humming after turning on A/C

DTC error codes

P0645

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Technical diagnosis (Premium)

Recognized technical fault:

Auxiliary controller voltage instability detected

Technical analysis

Detailed analysis of HVAC controller operation parameters, CAN bus data readings, and diagnostic signal waveforms. Purchase PRO access or log in to read the full fault analysis.

Confirmed solution

Complete step-by-step repair procedure including module non-volatile memory reset, sensor calibration, and correct wiring routing. Unlock the full report to see the instruction.

Parts needed

Filters ferrite anti-interference / noise suppressor
Auxiliary starting battery (depending on cell status)

Workshop hacks

Important workshop tips for mechanics regarding bypasses without expensive control module replacement and manufacturer software service bulletins.

TSB / TPI service bulletins

TSB-24-HVAC-01TPI-2068943/2

A/C Technical Specifications

Refrigerant specifications for this model are available in the catalog.

Open refrigerant database

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