Removing and installing heat exchanger for high-voltage battery — VW

🧭 Before you start

Fits: VW Golf VII Variant (BA), VW Golf VII (5G, 2012–2020)

• Special tools named: 3094
• Also covered elsewhere: Electronic Parts Catalogue

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• To prevent the intrusion of moisture, all components of the refrigerant circuit which have been opened must be sealed with suitable plugs.
• The heat exchanger is designed for a particular direction of flow of the coolant. Therefore, the coolant hoses must not be interchanged when connecting them.
• Bracket (F) is secured to the heat exchanger (E) with two bolts (G).
• If fitted, check that dowel pin (4) is not damaged and is seated correctly.Moisten seals with refrigerant oil before installing .Make sure seals are seated correctly in groove of corresponding refrigerant line.
• Bracket (F) is secured to the heat exchanger (E) with two bolts (G). If the bolts (G) have been loosened, insert them, but do not tighten them yet.

🔩 Torque settings

Values can differ between engine variants — check the code stamped on your block.

ℹ️ Always cross-check the exact figure against your vehicle's factory manual before final tightening — a wrong torque can damage the engine. These values are extracted from workshop data and may not cover every variant or revision.

📋 Procedure

1. Observe safety precautions Safety precautions when handling refrigerants.
2. Comply with notes Working on refrigerant circuit.
3. Observe safety precautions Safety precautions when working on the cooling system.
4. Observe safety precautions when working in the vicinity of high-voltage components Safety precautions when working in the vicinity of high-voltage components.
5. Observe the risk category of the high-voltage system 00Risk category of the high-voltage system.

6. Extract refrigerant using air conditioner service station before opening refrigerant circuit. [Note: To prevent the intrusion of moisture, all components of the refrigerant circuit which have been opened must be sealed with suitable plugs.]
7. Switch off ignition.
8. Open filler cap on coolant expansion tank for high-voltage system 19Cooling system, coolant.
9. Detach coolant expansion tank for coolant circuit of engine from vehicle, and slightly tilt it to the side 19Cooling system, coolant.
10. Clamp off coolant hoses (A) and (B) using hose clamps 3094. [Note: The heat exchanger is designed for a particular direction of flow of the coolant. Therefore, the coolant hoses must not be interchanged when connecting them.]
11. Cover area beneath connections for coolant hoses on heat exchanger (E) with absorbent paper.
12. Disconnect coolant hoses (A) and (B) from connections on heat exchanger (E).
13. Seal open connections for coolant hoses on heat exchanger (E) with clean plugs from engine bung setVAS 6122.
14. Remove bolts (F) on refrigerant lines to heat exchanger (E).
15. Remove bolts (D).
16. Detach heat exchanger (C) from refrigerant lines (B) and (C), and remove it together with bracket (F).
17. Seal open connections for coolant hoses on heat exchanger (E) and refrigerant lines (B) and (C) with clean plugs from engine bung setVAS 6122. [Note: Bracket (F) is secured to the heat exchanger (E) with two bolts (G).]
18. Renew seals (D); for correct version refer to Electronic Parts Catalogue.
19. Check connections of refrigerant lines ((B) and (C)) and on heat exchanger (E) for soiling and damage.
20. Insert seal (3) into groove (arrow) on connection of refrigerant line (1). [Note: If fitted, check that dowel pin (4) is not damaged and is seated correctly.Moisten seals with refrigerant oil before installing .Make sure seals are seated correctly in groove of corresponding refrigerant line.]
21. Bracket (F) is secured to the heat exchanger (E) with two bolts (G). If the bolts (G) have been loosened, insert them, but do not tighten them yet.
22. Install refrigerant lines (B) and (C) to heat exchanger (E), and secure them with bolts (A) (do not tighten bolts (A) yet).
23. Align heat exchanger (E) free of stress, and insert bolts (D).
24. Tighten bolts (G) (specified torque 8 Nm). — 8 Nm (5.9 lb-ft)
25. Tighten bolts (D) (specified torque 8 Nm). — 8 Nm (5.9 lb-ft)
26. Tighten bolts (F) (specified torque 8 Nm). — 8 Nm (5.9 lb-ft)
27. Connect coolant hoses (A) and (B) to connections on heat exchanger (E).
28. Fill coolant in coolant expansion tank for high-voltage system 19Cooling system, coolant.
29. Slightly increase pressure in coolant expansion tank for high-voltage system using e.g. cooling system testerV.A.G 1274 B19Cooling system, coolant.
30. Carefully open bleeder valve (C).
31. Carefully open hose clamp 3094 on coolant hose (A), and let coolant flow into heat exchanger (E).
32. As soon as coolant escapes from bleeder valve (C), close bleeder valve (C). [Note: If the heat exchanger for high-voltage battery (E) has been removed and installed as described above, there should not be any air in the coolant circuit of the high-voltage system. If, however, there is still air in the coolant circuit, bleed coolant circuit 19Cooling system, coolant.]
33. If necessary, fill coolant in coolant expansion tank for high-voltage system 19Cooling system, coolant.
34. Remove hose clamp 3094, and reinstall all components which have been removed or detached.
35. The remaining steps for installation are carried out in reverse order.
36. As a final step, read event memory, and clear any entries displayed using cooling system tester in "“Guided fault finding”" mode.

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