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Air conditioning stopped cooling / no response to AC button

Q: What are the symptoms of Air conditioning stopped cooling / no response to AC button in Honda Ridgeline?

No cold air from vents. Problem visible at standstill or in traffic

Q: How to fix Air conditioning stopped cooling / no response to AC button in Honda Ridgeline?

A quick diagnosis is to temporarily replace the AC clutch relay with an identical horn relay. If the air conditioning comes to life, a new, original and improved relay should be installed (updated Mitsuba or Denso parts are recommended). This avoids unnecessary replacement of the entire compressor.

in Honda Ridgeline (2002-2022)

Symptoms

No cold air from vents
Problem visible at standstill or in traffic

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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Air conditioning stopped cooling / no response to AC button

Symptoms

DTC error codes

A/C Technical Specifications

Other problems in Ridgeline

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