2021 Audi Vehicles Insufficient Cabin Heating TSB

Audi has issued Technical Service Bulletin (TSB) 2062583/2 to address customer concerns regarding Audi insufficient cabin heating and discolored engine coolant in various 2021 Audi models. This TSB supersedes an earlier bulletin, 80 21-11, and provides updated procedures for diagnosing and resolving the issue.

The primary cause identified is contamination within the engine coolant, which can lead to obstructions in the heater core. This blockage prevents proper heat transfer, resulting in poor cabin heating performance.

Symptoms

Owners of affected 2021 Audi vehicles may experience the following symptoms:

• "Insufficient or uneven cabin heating performance from the HVAC system."
• "The cabin heating may be slow to get warm."
• Engine coolant that appears discolored, showing signs of suspended particulate matter or a brownish tint.

These symptoms indicate a potential issue with the heater core's ability to circulate coolant effectively, impacting the overall cabin comfort.

Diagnosis

Technicians can diagnose this problem by observing a significant temperature difference between the inlet and outlet hoses of the heater core. If the inlet hose is considerably warmer than the outlet hose, it suggests an obstruction within the heater core.

Important Warnings

When working with the cooling system, technicians and owners should be aware of the following safety warning:

• "Risk of scalding due to hot coolant. The cooling system is under pressure when the engine is warm. Risk of scalding due to hot steam and hot coolant."

Repair Procedure Summary

The repair involves a comprehensive cleaning and flushing of the cooling system to remove contaminants and restore proper heater core function. The procedure includes several steps:

1. Coolant Drain: The cooling system is drained while the engine is warm and the thermostat is open.
2. Heat Exchanger Flush: The heat exchanger(s) are flushed with water in the opposite flow direction, ensuring water pressure does not exceed 2 bar.
3. Coolant Blow-Out: Coolant is blown out of the heat exchanger(s) in the opposite flow direction.
4. Cleaning Solution Application: 3.0 liters of cooling system cleaner 'S' (part number G 052 525 A3) are added, and the system is filled with coolant. The engine is run for 90 minutes with the cabin heating set to full hot and high fan speed.
5. Cleaning Solution Drain: The cleaning solution is then drained from the system.
6. Neutralizer Application: 3.0 liters of neutralizer 'S' (part number G 052 525 A3) are added, and the system is filled with coolant. The engine is run for 15 minutes with the cabin heating set to full hot and high fan speed.
7. Neutralizer Drain: The neutralizer solution is drained.
8. Distilled Water Flush: The cooling system is filled with plain distilled water, and the engine is run at approximately 2000 rpm until the cooling fans activate, continuing for an additional 3 minutes. This process is repeated for a total of two rinse cycles.
9. Final Drain: The distilled water is drained after the rinse cycles.
10. Expansion Tank Inspection: If the coolant expansion tank remains discolored after the cleaning process, it must be replaced.
11. Final Coolant Fill: The cooling system is refilled with the proper mix ratio of G12 evo coolant and distilled water.

It is crucial to note: "Do not reuse any of the cleaning and coolant solutions used during this process." The heater core should only be replaced if normal cabin heating performance is not restored after this cleaning and flush procedure, and an obstruction is confirmed as the root cause.

Required Tools or Parts

Technicians will use specific tools and parts for this repair:

• Cooling system cleaning set: Part number G 052 525 A3
• Neutralizer 'S': Part number G 052 525 A3
• Coolant: Approximately 30 liters
• Analog Refractometer: Tool number T10007B
• Cooling system charge kit: Tool number VAS 6096
• Adapter: Tool number VAG 1274/X
• Fasteners, bolts, nuts, and screws as needed per the repair manual.

Warranty Information

This repair is covered under Audi's warranty for up to 48 months or 50,000 miles. For Certified Pre-Owned (CPO) vehicles, verify ownership. If the vehicle is outside of warranty, this TSB serves as informational guidance only. The service number for this procedure is 8023, with a damage code of 0016. Various labor operations are specified, including 1938 17XX, 8023 2999, 8823 2999, 0150 0000, 0121 0002, and 0121 0004.