2023-2024 BMW X3, X4, 228i AC Rattling Noise TSB SIB 64 05 21

Symptoms

Owners of various BMW models, including the 2023-2024 BMW X3, X4, and 228i, may experience a distinct "rattling/droning noise" inside the vehicle cabin when the air conditioning (AC) system is active. This noise is often accompanied by noticeable vibrations felt in the driver's footwell. This specific BMW AC rattling noise issue is addressed by Service Information Bulletin (SIB) 64 05 21.

Cause of the Noise

The root cause of this BMW AC rattling noise is physical contact between the refrigerant line double pipe and a clamp located on the return line of the internal heat exchanger. This contact occurs on the left (driver's) side of the engine compartment, specifically below and behind the Digital Motor Electronics (DME) unit. The constant vibration from the engine and AC system causes these components to rub against each other, generating the audible rattling and droning sounds.

Repair Procedure Summary

BMW Service Information Bulletin SIB 64 05 21 outlines a two-step correction process to eliminate the rattling noise. Technicians will first install a spacer in the engine compartment. If the noise persists, additional steps involving felt tape and a hose clamp are performed.

1. Install a Spacer: A spacer (part number 11 53 7 537 923) is mounted in the engine compartment between the coolant hose feed and return lines. The coolant hoses must be carefully turned approximately 10 to 15 degrees towards the bulkhead to create proper clearance.

2. Apply Felt Tape and Hose Clamp (if needed): If the rattling noise continues after the spacer installation, the trim panel for the pedal mechanism must be removed (referencing repair instructions REP 5145186). Two heat exchanger lines are then taped with a felt strip (part number 51 45 2 353 024), each strip being 4-5 inches (10-12 cm) long. These lines are then secured together using a worm-type hose clamp (part number 07 12 9 952 117). This measure prevents the lines from moving within the aperture grommet. Finally, the trim panel for the pedal mechanism is remounted.

Required Parts

To perform the repair described in SIB 64 05 21, specific parts are required:

Part Number	Description	Quantity
51 45 2 353 024	Felt tape	25cm max
07 12 9 952 117	Hose Clamp	1
11 53 7 537 923	Spacer (originally for E83 vehicles)	1

Technicians should confirm the correct part numbers for a specific vehicle by entering the chassis number into the Electronic Parts Catalog (ETK) or Aftersales Information Research (AIR) system.

Warranty Information

This repair for the BMW AC rattling noise is covered under the terms of the BMW New Vehicle Limited Warranty for Passenger Cars and Light Trucks. The defect code associated with this issue is 6453003900, labeled as "Refrigerant line of Air conditioning Unpleasant noises."

Flat Rate Unit (FRU) allowances are provided for various labor operations:

• 12 90 150: Remove and install control unit box (Main work) - As applicable
• 12 90 650: Remove and install control unit box (Plus work) - As applicable
• 51 00 001: Body equipment / Localizing body complaint(s) (Work time) - WT FRU
• 00 58 500: Diagnosis Worktime Flat Rate - 2 FRU
• 64 99 000: Work time to install the clamp and felt strip - 2 FRU (or 4 FRU if taping both lines)
• 51 45 684: Removing and installing trim panel for pedal assembly - As applicable
• 51 45 184: Removing and installing trim panel for pedal assembly (Main work) - As applicable (for repairs prior to March 2022 Bulletin)

Only one instance of labor operation 64 99 000 should be claimed, either for 2 FRU or 4 FRU, depending on the work performed. Sublet Code 4 is used for reimbursement of repair-related bulk materials.

Important Notes for Technicians

This Service Information Bulletin (Revision 4) supersedes the previous SI B64 05 21 dated October 2022. The updated bulletin includes additional affected models and revisions to the claim information section. Labor operation codes 51 00 001 and 00 58 500 are not considered Main labor operations. For detailed procedures on documenting and claiming diagnosis work time, technicians should refer to SI B01 01 20 or B01 07 20. Supporting videos, BV64 01 22 and BV64 02 22, are available to assist with diagnosis and repair.

NHTSA ID: 10255866