Note:
This document is understood to be a supplement to the DAS function check "Refrigerant circuit test". Only perform repair and replacement work on the refrigerant circuit when the DAS check of the refrigerant circuit failed and corresponding instructions are available in the DAS function check "Refrigerant circuit test".
The exact quantity of refrigerant in the refrigerant circuit must be determined first, before replacing a part.
Filling in too little fluid may cause poor air conditioning system performance.
Too little refrigerant can also cause the air conditioning system to shut off or malfunction.
If the refrigerant circuit is insufficiently filled, the leak test (Test 6 "Refrigerant circuit leak") based on the "Technology Guide - Vehicle A/C system" must be performed first, then the system should be filled and checked again.
The refrigeration circuit contains too little refrigerant if the level has dropped to below 80 % of the standardized filling quantity.
Complaint:
Air conditioning system not working or performance is poor.
Cause:
There are several possible causes:
Defective refrigerant compressor (for remedy, see point 1 or 2)
System clogged (for remedy see point 3)
Remedy:
1 Refrigerant compressor has an electrical defect (regulation valve):
Note: Identification through DAS function check "Refrigerant circuit test", refrigerant circuit was not insufficiently filled (less than 80 % of the standardized filling quantity) or overfilled:
Replace the refrigerant compressor only.
2 If the torque limiter (limiter) on the refrigerant compressor is broken: (for fast diagnosis refer to Technology Guide for Automotive Air Conditioning - Knowledge base - Explanation on refrigerant compressor shaft) the generator freewheel should be checked, because the limiter may also intervene if the generator freewheel is defective (refrigerant compressor rotates).
The oil is to be checked for contamination (color dark gray - black).
If soiled, the air conditioning system must be flushed.
3 System clogged:
Note: Identification through DAS function check "Refrigerant circuit test", refrigerant circuit was not insufficiently filled (less than 80 % of the standardized filling quantity) or overfilled:
When completely refilling the air conditioning system, always ensure that the correct quantity of refrigeration oil and refrigerant are used. Check whether individual components or whether every component must be replaced.
A leak test must always be performed after the refrigeration circuit has been replaced and prior to filling with refrigerant.