High Priority 90% confidence

Unusual noise and metallic grinding when A/C is on

Q: What are the symptoms of Unusual noise and metallic grinding when A/C is on in Land Rover Discovery 3/4?

No cold air from vents. Different temperature on both sides of the cabin. Unusual noises when A/C is turned on

Q: How to fix Unusual noise and metallic grinding when A/C is on in Land Rover Discovery 3/4?

(1) TUBES: 'Rear AC Bypass' or 'Rear AC Lines Replacement' kit (rubber hoses instead of aluminum) - a much cheaper option. (2) VALVE: Replacing the Sanden control solenoid valve without removing the entire compressor. Rear AC Bypass kits on Allegro/Ebay cost PLN 300-600 vs. original tubes PLN 2,000-4,000. Durability is similar with good quality hoses.

in Land Rover Discovery 3/4 (2004-2020)

Symptoms

No cold air from vents
Different temperature on both sides of the cabin
Unusual noises when A/C is turned on

DTC error codes

Rear zone low pressure

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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

V (L462)

Refrigerant: R1234yf Amount (g): 800g Oil: PAG YF PAO 68 AA1 lub PAG ISO 46 YF Oil (ml): 90ml

Sport (L550)

Refrigerant: R1234yf Amount (g): 650g Oil: PAG YF PAO 68 AA1 lub PAG ISO 46 YF Oil (ml): 150ml

IV (LA) 2,7 TDV6

Refrigerant: R134a Amount (g): 550g Oil: ND8 PAO 68 lub PAG ISO 46 Oil (ml): 135ml

See full specification

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