Measures Required for ALL HVAC Concerns
Topic number

LI83.30-P-079850

Version

2

Function group

83.30 - Air conditioning

Date

1/15/26

Validity

All Mercedes Benz Passenger Cars

Reason for change

Remedy

Complaint
Customer states the AC either does not cool/has poor performance or heat is insufficient.

Cause
Many possible root causes

Remedy
AC Diagnosis (General)
Initial Steps
Verify Customer Concern

•

Confirm the issue reported by the customer.

Compare to Like Vehicle

•

Determine if the behavior is normal by comparing with a similar vehicle.

Determine Your Game and Players

•

Identify the diagnostic strategy and involved components/systems.

Testing

•

Perform relevant diagnostic tests.

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Refrigerant Quantity

•
•

Record the amount of refrigerant recovered and compare it to the specified value (if applicable).
Forming Gas is the ONLY approved leak test method. (DYE is NOT approved)

TIPS Case Submission Requirements/Warranty Claim Submission Requirements
Cooling Capacity Test (If System Has a Charge)
*Note - TIPS case is only required if the root cause is not identified or other Li's/documents require a case to be open.

Before Repairs

Gauge Readings

•

High and Low pressure readings (from machine or separate gauges).

Leak Detection (if applicable)

•

PPM of any leaks found.

XENTRY Printouts

•
•

Climate control AVs.
HV compressor AVs (for heat and AC systems).

Thermometer Readings

•
•

Left and right dash vents.
Center vent, footwell, and/or rear vents (if concern is localized).

Ambient Conditions

•

Temperature and humidity from OCP AVs (if available).

After Repairs
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Gauge Readings

•

High and Low pressure readings before and after repairs.

Thermometer Readings

•
•

Left and right dash vents before and after.
Center vent, footwell, and/or rear vents before and after (if localized concern).

Documentation

•
•
•
•

Complaint Analysis, Game/Players, and Testing Steps.
Include expected results and technical justification for the diagnosis.
Avoid listing R/I steps—focus on diagnostic reasoning and root cause.
All prior measurements need to be documented on the repair order.

OP code usage:
831232 - Max .5 for Cooling Capacity Test
831040 - Only to be utilized if you have a fault code and are actively diagnosing that fault code (MAX 1 hour)
831762 - This includes basic leak check
831285 - This can only be used in extenuating circumstances where a leak cannot be found (MAX 1 hour)

Disclaimer
NOTE: The information contained in this document is intended for use by trained, professional technicians with the
knowledge to properly and safely perform diagnosis and repairs on Mercedes-Benz vehicles, using Mercedes-Benz
approved tools and equipment. It informs service technicians about conditions that could occur in certain vehicles and
provides information that could assist in proper vehicle diagnosis, service, or repair. It does not indicate that a defect
is present in any vehicle referenced in this document nor does it imply warranty coverage. DO NOT assume that a
symptom or condition, or a described cause of a symptom or condition, affects any particular vehicle or groups of vehicles, or that a described repair applies to any particular vehicle or groups of vehicles. There can be multiple causes
resulting in the same or similar symptoms or conditions described in this document, and trained professional service
technicians must use their diagnostic skills to make evaluations on a case-by-case basis. The information contained
in this document does not guarantee warranty coverage nor does it extend the vehicle’s warranty in any way.

Symptoms
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
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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

Operation numbers/damage codes
Op. no.

Operation text

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Time

CCUSHWA

Damage
code

Note

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