2021 Mercedes-Benz AMG GT HVAC Performance Issues

Owners of 2021 Mercedes-Benz AMG GT vehicles may experience various issues with their heating, ventilation, and air conditioning (HVAC) system. This technical service bulletin (TSB) L183.30-P-079850 provides a comprehensive guide for technicians to diagnose and address these concerns, focusing on the Mercedes-Benz AMG GT HVAC performance.

Symptoms

Customers may report the following symptoms related to their 2021 Mercedes-Benz AMG GT HVAC performance:

• The AC either "does not cool" or has "poor performance".
• The "heat is insufficient".
• Body > Air conditioning > Heater > "Remains cold".
• Body > Air conditioning > Heater > "Remains warm/hot".
• Body > Air conditioning > Heater > "Insufficient heat output".
• Body > Air conditioning > Heater > "Cold in footwell".
• Body > Air conditioning > Air conditioning > "Insufficient cooling output".
• Body > Air conditioning > Heater > "Malfunction, defrosting".
• Body > Air conditioning > Heater > "Footwell flap cannot be opened/closed".
• Body > Air conditioning > Air conditioning > "Temperature differences".
• Body > Air conditioning > Air conditioning > "Cooling output too high".
• Body > Air conditioning > Heater > "Center air vent does not close".
• Body > Air conditioning > Air conditioning > "Temperature control not sensitive enough".

Diagnosis and Troubleshooting for Mercedes-Benz AMG GT HVAC Performance

This TSB outlines a general AC diagnosis procedure for technicians. The initial steps involve verifying the customer's reported concern and comparing the vehicle's behavior to a similar, properly functioning vehicle to determine if the behavior is normal.

Technicians are instructed to:

1. Determine Diagnostic Strategy: Identify the appropriate diagnostic strategy and the involved components or systems.
2. Perform Relevant Diagnostic Tests: Conduct necessary tests to pinpoint the root cause of the Mercedes-Benz AMG GT HVAC performance issue.
3. Refrigerant Quantity Check: Record the amount of refrigerant recovered and compare it to the specified value. This step is crucial for proper AC function.
4. Leak Detection: If applicable, perform leak detection and record the Parts Per Million (PPM) of any leaks found.
5. Gauge Readings: Take high and low-pressure readings from the AC system before and after any repairs.
6. XENTRY Printouts: Obtain printouts for climate control AVs (Actual Values) and HV compressor AVs for both heating and AC systems.
7. Thermometer Readings: Measure temperatures at various vents (left and right dash, center, footwell, and rear) before and after repairs, especially if the concern is localized.
8. Ambient Conditions: Record temperature and humidity from OCP AVs (Overhead Control Panel Actual Values) if available.

Important Warnings

Mercedes-Benz specifies that "Forming Gas is the ONLY approved leak test method. (DYE is NOT approved)" for refrigerant leak detection. Technicians should strictly adhere to this guideline to ensure proper diagnosis and avoid potential system contamination or damage.

This document is intended for trained, professional technicians. It provides information that could assist in vehicle diagnosis, service, or repair but does not indicate a defect or imply warranty coverage. It's important to note that a symptom or condition described does not necessarily affect all vehicles or groups of vehicles, and multiple causes can lead to similar symptoms. Technicians must use their diagnostic skills for case-by-case evaluations.

Required Documentation

For proper diagnosis and warranty claims, technicians must document the following:

• A thorough complaint analysis.
• Details of the diagnostic strategy and testing steps performed.
• Expected results and technical justification for the diagnosis.
• All prior measurements must be recorded on the repair order.
• Avoid listing only