Mercedes Benz Truck R 320 BLUETEC Technical LI83-00_P-047480 Date: 090729
A/C - No Or Insufficient Cooling Output
NO OR INSUFFICIENT COOLING OUTPUT, PERMANENTLY OR OCCASIONALLY/DEFECTIVE REFRIGERANT LINE
Topic Number LI83.00-P-047480
Version 1
Design Group 83.00 general
Date 07-29-2009
Validity Passenger car model series with air conditioning
Reason for change
Reason for block
COMPLAINT:
No or insufficient cooling output, permanently or occasionally/defective refrigerant line.
CAUSE:
Refrigerant line (engine-side low-pressure line, from compressor to connecting point upstream of expansion valve) whose inner coating comes loose
in the flexible section of the hose, causing constriction.
Attachments
REMEDY:
Air conditioning system may not be evacuated before test steps 1. - 3., this could affect the test result.
1. Start engine, activate air conditioning on control panel (max. cold, blower setting 3), medium engine speed.
2. Connect pressure gauge to high and low-pressure side.
3. Check whether the refrigerant compressor is delivering refrigerant (limiter on belt pulley turns or pressure builds up in refrigeration circuit): If the
refrigerant, eliminate this fault.
If the refrigerant compressor builds up pressure,
4. Read off the high and low-pressure values from the pressure gauges after approx. 5 minutes.
If the installation space does not permit reliable temperature measurement using an infrared thermometer, continue with 6:
5. If the low pressure is noticeably high (> approx. 60psi) and the evaporator temperature is significantly too high at the same time (> approx. 50°F)
use an infrared thermometer to check the engine-side low-pressure line against the refrigerant flow direction (from compressor to connecting point
upstream of expansion valve). If there is a noticeable temperature drop in the line (Delta > 45°F),
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6. Dissemble the engine-side low-pressure line (from compressor to connecting point upstream of expansion valve) and
7. Use an endoscope or the procedure described in the attachment to check the line for clear passage (checking for clear passage using welding wire
or similar is not permissible as this can damage the inner hose and cannot detect peeling anyway).
8. Replace the line if you detect and constriction. Refer to EPCNet for applicable part number.
Attachments
Symptoms
Parts
Work units
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Validity
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Attachments - Visual inspection of intake line for clear passage
