Cooling System: Testing and Inspection

Cooling system, checking for leaks





Special tools and equipment
^ Cooling system tester V.A.G. 1274
^ Adapter V.A.G. 1274/8
^ Adapter V.A.G. 1274/9

Requirement:
^ Engine warm

Work sequence

WARNING: Hot vapor/hot coolant may escape when opening expansion tank. When opening the expansion tank, wear gloves and other appropriate protection. Cover the cap with a rag and open carefully to relieve pressure slowly

- Unscrew cap of coolant expansion tank.





- Position tester V.A.G. 1274 with adapter V.A.G. 1274/8 on expansion tank.
- Use hand pump to generate a pressure of approximately 1.0 bar.
- If there is a drop in pressure, locate leak and eliminate malfunction.





Checking pressure relief valve in cap
- Position tester V.A.G. 1274 with adapter V.A.G. 1274/9 on cap.
- Operate hand pump.
^ Pressure relief valve must open at a pressure of 1.4 to 1.6 bar

Coolant fans -V7- and -V177-
Function
The cooling system is provided with 2 coolant fans:
^ Coolant Fan -V7- on left in direction of travel with Coolant fan control (FC) control module J293-.
^ If there is a drop in pressure Coolant Fan -2- V177- on right in direction of travel with coolant fan control (FC) control module 2 -J671-.
Both fans are actuated with infinitely variable control by the engine control module via the corresponding radiator fan control module.
^ Contact 66 of the engine control module is the control output for coolant fan control module 1.
^ Contact 104 of the engine control module is the control output for coolant fan control module 2.

The coolant fans are actuated on the basis of the following criteria:
^ Fan request from air conditioner: Fan request is transmitted from air conditioner operating element via CAN bus to engine control module, from where it is relayed directly to the fans
^ Normal engine operation: In normal operation and with engine idling, fans are controlled as a function of coolant and ambient temperatures.