Installing air conditioning unit (front): Audi Q7

🧭 Before you start

With a helper, check seals and caps, set the unit in place and secure it to the plenum back wall, then refit bolts, cable ties, drain hose and dash cross member. Connect coolant hose A, fill the expansion tank and pre-bleed the heat exchanger before connecting hose B. Refit the rest, evacuate and recharge the refrigerant circuit, leak-test and bleed the coolant, then clear faults, run basic setting and start the air conditioner.

Fits: Audi Q7 (4L, 2005–2015)

• Special tools named: VAS 5051
• Renewed: damaged seals

Don't miss

• Check the caps on the evaporator connections are firmly attached so they are not damaged during fitting.
• Only use hexagon nuts with an intact rubber layer at the plenum chamber back wall.
• Connect hose A first and pre-bleed the heat exchanger until coolant emerges at hose B.
• Bleed the heat exchangers completely; trapped air gives weak heat or uneven vent temperatures.
• Leak-test the coolant pipe-to-heat exchanger joint under pressure before closing up.
• Clear fault memories and run basic setting after charging the refrigerant circuit.

Written for this job from the workshop steps below · TorqFix editorial.

📋 Procedure

1. The assistance of a 2nd mechanic is required when installing the air conditioning unit.
2. Check the correct positioning of the bonded rubber elements (A) in the air conditioning unit (bond into mounts of air conditioning unit (F) if necessary).
3. Check the positioning of the caps (B) and (C) at the connections to the evaporator. These must be firmly attached to avoid damaging the connections on installing the air conditioning unit.
4. Check the foam seal (D) for correct positioning and damage.
5. Check that grommet (E) is not damaged and is seated correctly on flange of coolant pipes. [Note: Before installing, also check all other seals at air conditioning unit for damage and renew damaged seals.]

6. Insert the air conditioning unit and attach it to the plenum chamber back wall using the two hexagon nuts with washer (C). [Note: On tightening the hexagon nuts (C), pay attention to correct positioning at the plenum chamber back wall (in line with mark made).Only fit hexagon nuts with washer (C) provided with an intact rubber layer (D) for sealing purposes.]
7. Re-install all bolts in line with assignment on removal.
8. Re-install all cable ties and other wiring harness fasteners released or severed on removing the air conditioning unit in the same position.
9. Attach the condensation drain hose to the air conditioning unit .
10. Fit the dash panel cross member and attach the air conditioning unit to the dash panel cross member at the intended locations General body repairs, interior70
11. Insert the grommet (C) in the plenum chamber back wall and then check the positioning of the grommet (C) on the flange of the coolant pipes (in the passenger compartment).
12. Attach the coolant hose (A) to the coolant pipe to the heat exchanger (coolant hose (B) is not connected yet). [Note: Correctly connect up the coolant hoses: Coolant hose (A), supply from engine (via pipe assembly beneath left wing) and coolant hose (B), return to engine (via pipe assembly beneath left wing)]
13. Fill the coolant expansion tank with coolant as far as the upper mark.
14. Slacken off the hose clamps up to dia. 25 mm3094 at the coolant hose (A) to enable the coolant to flow slowly into the heat exchanger (to pre-bleed the heat exchanger). [Note: If the coolant does not flow automatically into the heat exchanger, build up pressure in the coolant expansion tank using the hand pump of the cooling system testerV.A.G 1274 for example to accelerate the flow process.Pre-bleeding of the coolant circuit considerably simplifies the bleeding of the cooling system on initial commissioning following installation .Bleeding coolant circuit and Engine, mechanics19]
15. Wait until coolant emerges from the connection for the coolant hose (B) at the coolant pipe to the heat exchanger.
16. Attach the coolant hose (B) to the coolant pipe to the heat exchanger.
17. Re-install the remaining components removed in reverse order with the exception of the cover beneath the dash panel on the left.
18. Evacuate and re-charge the refrigerant circuit Air conditioner with refrigerant R134a87Refrigerant circuit (air conditioner with refrigerant R134a, refrigerant circuit, working with air conditioner service station). [Note: Also heed the information on start-up of the air conditioner after charging Air conditioner with refrigerant R134a87General information on air conditioner (air conditioner with refrigerant R134a, general information on air conditioner). Before starting up air conditioner after fresh charging.]
19. Check the coolant circuit for leaks, paying particular attention to the connection between the coolant pipes and the heat exchanger Engine, mechanics19 [Note: After filling, check coolant circuit for leaks e.g. as follows: Open cap at coolant expansion tank (observe safety precautions when opening cap Engine, mechanics19) and then increase pressure in coolant circuit, e.g. using hand pump from cooling system testerV.A.G 1274/Engine, mechanics19.]
20. Bleed coolant circuit and Engine, mechanics19 [Note: When bleeding the coolant circuit, take particular care to ensure that the heat exchangers are bled completely. If air bubbles remain in the heat exchanger, complaints may be received about a lack of heat output in winter or differences in the temperature of the air flowing out of the vents with the same setting in control mode .]
21. Re-install the bottom left dash panel trim.
22. Interrogate the fault memory of the front operating and display unit, Climatronic control unit J255 and the rear Climatronic operating and display unit E265 and erase any faults displayed. "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051.
23. Perform basic setting and final control diagnosis for air conditioner Guided Fault Finding function of vehicle diagnostic, testing and information system VAS 5051.
24. Start up air conditioner after charging refrigerant circuit .
25. If necessary, check operation of the air conditioner "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051.

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