Heater Core Swap

by: jjwb55



I did the swap on a 2000 V6 manual with climatronics.
MJ did the swap on a 1998 1.8T manual with manual HVAC.
I did the swap without disconnecting the A/C. While completing the swap is possible without touching the a/c lines, there is a much greater chance of breaking something if you aren't careful where you put force. It will be more of a pain. You will need a friend. MJ had a local shop discharge the AC system. The total cost for discharging and recharging was $120.

also see Heater Core Flush


  • 8mm, 10mm and 17mm sockets
  • T-20 torx socket
  • T-25 torx socket
  • 6mm Allen socket
  • Flexible shaft socket driver
  • 1/4” socket driver with short handle
  • 3/8” socket driver
  • 1/4” & 3/8” short & long extensions
  • Universal joints
  • #1 phillips screwdriver
  • Flathead screwdriver
  • Radio removal tools


  • 8d1-819-031-c 98-05 volkswagen passat heater core ( please confirm correct part #)

1. If disconnecting A/C lines, have a shop discharge the system. Park the car with the tires straight and move the front seats all the way back.

2. Disconnect the battery and touch ends to discharge completely. (10mm)

3. Drain coolant until expansion tank is empty.

4. Remove fuse panel cover. Remove the (2) T-25 & (2) 8mm screws.

5. Remove light switch. Push in, turn right, and pull out. Disconnect the harness.

6. Remove (2) 8mm screws on the lower part of the lower kick panel. Pull the panel out and disconnect the dash light adjuster and OBD2 plug.

7. Remove the (5) 8mm screws on the metal kick plate.

8. Loosen the steering column cover from the dashboard by removing the (2) small Phillips (or T-20) screws from below.

9. Remove the (2) upper T-20 screws from the trim piece that surrounds the steering column. This is where the flexible shaft for the bit driver is required. They have been removed already in this picture but their position is shown with the trim pulled forward. You must remove the (4) above mentioned T-20 screws to move this trim piece.

10. Lower the steering wheel and pull it out as far as possible. Slide the trim piece that surrounds the steering column back from the cluster and remove the (2) t-20 screws holding in the cluster. The flexible plastic shroud can be moved with little chance of damage:

11. By grabbing the lower edge of the cluster you can wiggle it out of the dash. Disconnect the blue connector (left-side) and green connector (right-side) from the back of the cluster by flipping upward the dark-pink lever attached to the back of each connector.

12. Remove the radio with the proper tools. If you have the Climatronic control, pry off the cover to reveal (4) T-20 torx screws and unplug the harnesses. Where the (4) torx screws mounted the Climatronic unit, remove the (4) metal clips. Pull the face plate out.

13. To remove the manual hvac controls first pry the cover plate using a small screwdriver.

14. Remove the (4) T-20 screws around the control knobs and the (2) T-20 screws in the cubby below.

15. Now you can slide out the entire trim frame. Disconnect the switches from the wiring harness.

16. The manual control unit is now free. Study the position of the control wires and housing to be sure you reinstall them in their proper locations later on. Remove the (3) control wires and the (2) harness connectors.

17. There are T-25 screws in the circled locations. Pull the cage out.

18. Remove the 2 covers and 8mm screws, pop out the bottom of shifter boot, lift up the front side (where the screws were) and pull out, sliding the shifter boot though the hole and disconnecting the cig lighter.

19. Remove the (2) T20 screw on the bottom of the main dash that were covered by the ashtray.

20. Remove the trim panel on both sides. T-25.

21. Remove the foot well door pillar trim under the right side of the glove box. T-20 or phillips + press-on connector.

22. Remove the (2) T-20 screws on the bottom of the glove box. Open the glove box and remove the (5) screws along the top. From the top, carefully pry out the light & trunk release (if you have it) and disconnect. The light mechanism may (will) come apart in a bunch of small pieces. Look here for guidance on reassembly. Carefully remove the glove box.

23. Pry off the right side dash cover and remove (4) T-25 screws similar to the fuse panel side. Disconnect the connector in the opening. A sheet metal bracket that supports the removed glove box will now be accessible for removal.

24. Remove the (2) T-25 screws deep under either side of the steering column.

25. Carefully pry up and disconnect the sunlight photo sensor (27) on top of the dash.

26. Remove the dash by pulling back and up. Be carefully any wiring doesnt catch. During reassembly, be sure to get the connector for the sunlight sensor back into the hole before putting the dash all the way on.

27. Unplug the airbag connector and remove the (4) 10mm bolts holding the passenger airbag brackets to the crossmember.

28. Remove the bolts from the areas pictured. Vent 1 is pried out with a flat screwdriver from the threaded post on the right side, disconnect the wiring on the back side. Vent 2 and 3 just pop out.

29. Remove the remaining screws from #9 and remove. Remove the remaining screws on #8 except for the (3) connected to the hvac assembly. It should only be attached to the HVAC.

30. Loosen the (2) 17mm nuts on the driver’s side end of the crossmember. Leave on end to prevent it from coming off and jarring the steering components. Remove the nut on the far passenger side. You should be able to pull it away from the right side to gain room but not much yet.

31. To remove vent 4 pictured above, there are (2) 8mm bolts attaching it to the crossmember. These are a pain. I used a universal joint and extensions with a stubby socket wrench barely hitting the window…

32. Remove each “crumple zone” aluminum frame with (2) 10mm bolts on either side of the center dash console.

33. Unplug and remove the mysterious silver box where the airbag was. Underneath is a bracket mounting the HVAC assembly to the crossmember. Remove the (2) screws from the bracket into the crossmember.

34. Remove the bolt between the steering wheel and the control console connecting the cast aluminum frame for supporting the brake/ accelerator pedals to the crossmember with a 6mm allen socket.

35. In the engine bay, unhook the 2 hoses from the heater core and plug them. If you can, siphon out the coolant from the heater core. To disconnect the A/C, remove the bolt on the flange where the A/C leads into the firewall and carefully pry away. Block off the hoses to prevent debris and moisture from entering the pipes.

36. There are 3 screws holding the LH console bracket to the hvac assembly but should be free to move with it. If not, remove these screws and work out the bracket.

37. With the A/C disconnected, carefully remove the HVAC assembly. With the A/C not disconnected, grab a friend and carefully, but forcefully, pivot out the crossmember from the right side and the hvac from the left side until the heater core nipples clear the interior firewall shelf to allow removal. There are 2 phillips screws and 2 snaps on the top of the heater core. Pull it out, put the new one in, rewind.

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