Checking cooling output - vehicles with automatically controlled air conditioner — AUDI

🧭 Before you start

Fits: platform code FV

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• Measure ambient temperature: It must be over 15 °C.
• The operation of the air conditioner can be detected e.g. from the fact that the refrigerant pipe on the low-pressure side (thick pipe) cools down.

📋 Procedure

1. Measure ambient temperature: It must be over 15 °C.
2. Close doors, bonnet, windows, sunroof and rear lid.
3. Open all the dash panel vents and if fitted the vent in the rear centre console.
4. Start engine.
5. Make the following settings on the operating units for the air conditioning system: [Note: This illustration shows the position of rotary controls (1, 2, 3) and buttons (4, 5) on a vehicle with left-hand drive. On vehicles with right-hand drive, the position may be different. The displays for rotary controls (1, 2, 3) switch on and off together with the ignition.]

6. "“Read measured values”" ("“Guided Fault Finding”" for the J255).
7. Read out activation of air conditioner compressor regulating valve N280.
8. Read measured value of pressure sender for refrigerant circuit G805. [Note: On the absolute pressure scale, 0 bar corresponds to an absolute vacuum. Normal ambient pressure thus corresponds to approx. 1 bar absolute and 0 bar gauge pressure. On the scales of most pressure gauges, 0 bar gauge pressure corresponds to an absolute pressure of 1 bar (can be seen from -1 mark below 0).The pressure in the refrigerant circuit depends on the ambient temperature. Due to the radiation of heat by components (e.g. radiator), the pressure displayed when the engine is warm is slightly higher than that given for the corresponding ambient temperature.]
9. Check signal of G805 ("“Guided Fault Finding”" for the J255).
10. The necessary work may only be performed by appropriately qualified personnel. If this is not possible on your premises, the vehicle must be taken to a workshop equipped with the necessary tools where this work can be performed by appropriately qualified personnel Air conditioner with refrigerant R134a87General notes on air conditioning systems. Inform the workshop of the problem detected.
11. Make the following settings on operating unit J255:
12. "“Read measured values”" ("“Guided Fault Finding”" for the J255).
13. Check display in display zones:
14. Check again whether the air conditioner compressor is actually being driven and the air conditioner compressor regulating valve N280 actuated.
15. The necessary work may only be performed by appropriately qualified personnel. If this is not possible on your premises, the vehicle must be taken to a workshop equipped with the necessary tools where this work can be performed by appropriately qualified personnel Air conditioner with refrigerant R134a87General notes on air conditioning systems. Inform the workshop of the problem detected. [Note: N280 is activated by J255 so that the temperature of the air downstream of the evaporator reaches the specified value (approx. 2 to 6 ℃).After starting the vehicle, a value greater than 0.55 A is displayed for actuation of N280 depending on the measured temperature, engine speed and electrical system voltage. As soon as the temperature measured by the evaporator output temperature sender G263 approaches the specified value, actuation is cancelled and the air conditioner compressor output thus reduced.Under certain operating conditions, residual moisture in the refrigerant circuit may lead to the formation of ice at N280 and at the expansion valve. Such ice formation impedes the control of the air conditioner compressor. The evaporator is cooled down too much and ices up. An iced-up evaporator may cause various problems .If no current is displayed in the measured values for the activation of the air conditioner compressor regulating valve N280 or if the current is too low, check the activation of N280 ("“Guided Fault Finding”" for the J255).]
16. Press the air recirculation button (in the rotary control (4)) on the Operating and display unit 4 for air conditioning system E777.
17. Set the engine speed to 2000 rpm (start of time measurement).
18. "“Read measured values”" ("“Guided Fault Finding”" for the J255).
19. Compare the measured value displayed for the evaporator output temperature sender G263 to the values in the graph.
20. Compare measured values for left vent temperature sender G150 (or right vent temperature sender G151) to measured value displayed for evaporator output temperature sender G263 ("“Guided Fault Finding”" for the J255).
21. Use a thermometer to measure the temperature of the air emerging from the right dash panel vent (2) (left vent on vehicles with right-hand drive). [Note: The designation and installation location of the vent temperature senders (left vent temperature sender G150 and right vent temperature sender G151) are different. On vehicles with left-hand drive, the G150 is installed in the air duct to the left dash panel vent (1). On vehicles with right-hand drive, the G151 is installed in the air duct to the right dash panel vent (2).You can also use a thermometer to measure the temperature of the air emerging from the left (1) and right (2) dash panel vents.]
22. Perform Fault Finding measures to be taken if readout does not match specification .
23. Check that G263 is correctly installed and perform electrical check for this sender ("“Guided Fault Finding”" for the J255). [Note: The operation of the air conditioner can be detected e.g. from the fact that the refrigerant pipe on the low-pressure side (thick pipe) cools down.]
24. Perform the measures to be taken if the readout does not match the specification (required cooling output is not attained) .
25. Check activation of temperature flaps in heater/air conditioning unit and ("“Guided Fault Finding”" for the J255).

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