Audi Tech Tip: Rattle Noise From Engine Area – UnderhoodService

Audi Tech Tip: Rattle Noise From Engine Area

Rattle noise from the air conditioning compressor. The noise is particularly audible in ECON operation. When the compressor operates under load, the noise is hardly audible. This condition is exhibited only in vehicles equipped with a DENSO air conditioning compressor with a plastic pulley.
Damper elements of the plastic pulley are noisy under little or no compressor load.
Production Solution:
New compressor from model year 2008.
Service 
1. Check whether a plastic pulley is installed on the air conditioning compressor.
2. Make certain that the vehicle is in a temperature environment above 5° C (approximately 40° F), as a compressor shut off condition is active below this temperature.
3. Set the HVAC system to full cooling and listen for noise.
4. Activate ECON mode. If the noise is only present in ECON and not in full cooling, it is likely that the compressor pulley is the source of the noise.
5. Apply a noise-dampening foil (P/N 8E0 260 329) to the ­pulley. The air conditioning compressor does not have to be removed.
6. If this solution is not successful, replace the plastic pulley according to the repair information in ElsaWeb >> Heating, Ventilation & Air Conditioning >> Heating, Ventilation & Air Conditioning >> 87 Air Conditioning >> Compressor Belt Pulley/Drive Unit, Replacing.
Courtesy of MotoLOGIC Repair & Diagnostics:

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