Removing and installing left heat regulation valve N175 and right heat regulation valve N176 — AUDI

🧭 Before you start

Fits: platform code 42

• Special tools named: 3094

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• Coolant circulation pump V50 and heat regulation valve N175 / N176 faults are detected by the operating unit, Climatronic control unit J255 and stored if the ignition is switched on with the connector unplugged.

📋 Procedure

1. ⚠ Risk of burns.Even if the engine is cold, the heat regulation valve unit may be warm or even hot as, with the ignition on, it is constantly actuated as a function of the temperature setting at the operating unit, Climatronic control unit J255. — Switch off the ignition.
2. ⚠ Danger of scalding from hot vapour and hot coolantThe cooling system is pressurised when the engine is warm.To dissipate the pressure, cover the coolant expansion tank cap with a cloth and open carefully. — Open the coolant expansion tank cap.
3. Remove the cover for the transmission tunnel (1).
4. Remove the propshaft Rear final drive39.
5. ⚠ Risk of burns.Even if the engine is cold, the heat regulation valve unit may be warm or even hot as, with the ignition on, it is constantly actuated as a function of the temperature setting at the operating unit, Climatronic control unit J255. — Mark the arrangement of the coolant hoses (F) (supply to left heat exchanger) and (B) (supply to right heat exchanger) for re-installation.

6. Pinch off the coolant hoses (A, B, F) with hose clamps 3094.
7. Detach the pipe holder (C) from the stud.
8. Unscrew the nut below it.
9. Unplug the connector (D).
10. Detach the coolant hoses (A, B and F) from the heat regulation valve unit (E).
11. Detach the heat regulation valve unit. [Note: The coolant circulation pump V50 is not to be started up until the coolant circuit has been bled (dry running would destroy the coolant circulation pump V50).The two heat regulation valves N175 and N176 must be open for bleeding the coolant circuit (they are open when not actuated).]
12. Unplug the connectors at the heat regulation valve unit and the coolant circulation pump V50.
13. Bleed the coolant circuit 19.
14. Plug the connectors back in at the coolant circulation pump V50 and the heat regulation valve unit. [Note: Coolant circulation pump V50 and heat regulation valve N175 / N176 faults are detected by the operating unit, Climatronic control unit J255 and stored if the ignition is switched on with the connector unplugged.]
15. Install the propshaft Rear final drive39.
16. Fit the cover for the transmission tunnel 66.
17. Interrogate the event recorder and erase any faults displayed.
18. Implement final control diagnosis.

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