Checking signals from and to air conditioning system: VW Passat B5 2.3 (AZX)

🧭 Before you start

Fits: VW Passat B5 (3B)

• Special tools named: V.A.G 1551, V.A.G 1552, V.A.G 1598/31

Don't miss

• Observe display in display zone 4. It must show Compr. OFF.

🔧 Engine codes this applies to

📋 Procedure

1. Connect fault reader V.A.G 1551 (V.A.G 1552). Start engine and select "“Address word”" 01 of engine control unit. (Connect fault reader and select engine control unit )
2. Press keys 0 and 8 for function "“Read measured value block”" and confirm entry with Q key.
3. Press keys 0, 5 and 0 for "“Display group number 50”" and confirm entry with Q key.
4. Observe display in display zone 4. It must show Compr. OFF.
5. Switch on air conditioning system.

6. Set lowest temperature and highest blower speed.
7. Press → button.
8. Press buttons 0 and 6 for function "“End output”" and confirm entry with Q button.
9. Switch off ignition.
10. Connect test box V.A.G 1598/31 to control unit wiring harness. The engine control unit remains disconnected.
11. Check lines for open circuit between sockets 40 + 41 and air conditioner using current flow diagram. Cable resistance: max. 1.5 Ω.

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