What are the symptoms of Unusual noise and metallic grinding when A/C is on in BMW E36/8)?

No cold air from vents. Weak cabin cooling. Unusual noises when A/C is turned on

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Unusual noise and metallic grinding when A/C is on

Q: How to fix Unusual noise and metallic grinding when A/C is on in BMW E36/8)?

1) CLUTCH DIAGNOSTICS: With the engine running and the air conditioning on, directly power the compressor signal cable (usually one cable) with +12V. If the middle clutch plate 'clicks' and rotates together with the pulley - the problem is in the control system (relay, pressure sensor, ECU), not in the compressor. 2) LEAK: Check for oil stains around the hose connections, condenser (behind the radiator) and choke. Replacing the damaged element, replenishing PAG oil and refilling the system. 3) HEATER CONTROL VALVE: If, despite a functional compressor, summer air blows from the vents - check the heater valve (same problem as in E39/E46). Relay test: replace the AC relay with the radiator fan relay (same 30A parameters). If the air conditioning starts working after the replacement - the AC relay should be replaced for PLN 10,000 instead of the compressor costing thousands.

in BMW E36/8) (1995-2002)

Symptoms

No cold air from vents
Weak cabin cooling
Unusual noises when A/C is turned on

DTC error codes

No DTC codes (analog A/C system)

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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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