1996 AUDI A4 AHA ATQ Engines Cooling System Components Workshop Manual

19-27


If 1st or 2nd fan speed does not run:
Electrical Wiring Diagrams, Troubleshooting & Component Locations
If no open circuit can be found: - Bridge terminal -1- and terminal -3- of harness connector using
auxiliary cables from VW1594 connector test kit.
Coolant fan -V7- must run on 2nd speed.
- Locate and repair open circuit using wiring diagram:- Replace coolant fan -V7-.
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19-28

Cooling system, pressure test


Engine at operating temperature

WARNING!

The cooling system is pressurized when the
engine is warm. When opening the expansion
tank, wear gloves and other appropriate
protection, cover the cap with a cloth and
open carefully to relieve system pressure
slowly.

- Open cap on coolant expansion tank.

- Using VAG1274/8 adapter attach VAG1274 cooling system tester to
coolant expansion tank.
- Use tester hand pump to create a pressure of approx. 1.0 bar (14.5
psi).
- If pressure falls, check for leaks and repair.
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19-29

Pressure relief valve in cap, checking

- Attach sealing cap to tester using VAG1274/9
adapter.

- Install hand pump and pump.
- Pressure relief valve must open at pressure between 1.4-1.6 bar (20.3-
23.2 psi).
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19-30


After-run coolant pump

1 -
Coolant reservoir
Perform coolant system leak test using
VAG1274 cooling system tester and
VAG1274/9 adapter.
2 -
Lower coolant pipe
3 -
25 Nm
4 -
25 Nm
5 -
Bracket for after-run coolant pump
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19-31


6 -
Spring clamp
7 -
Coolant hose
8 -
Spring clamp
9 -
Electrical after-run coolant pump
Checking page 19
-32
Removing and installing page 19
-34
10 -
10 Nm
11 -
Spring clamp
12 -
Coolant hose
13 -
Spring clamp
14 -
Connection
For thermostat
15 -
Oil cooler
16 -
Oil filter
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19-32

After-run coolant pump, checking


Note:

Control modules with an after-run time of 15
seconds after engine is turned off were installed
since start of production. As a running change
in m.y. 1999, control modules with an after-run
time of 3 minutes were installed.
The coolant after-run pump also continues to
run after the engine is started again before the
15 second or 3 minute cycle is completed.
The coolant after-run pump and the after-run
fan are controlled via the same control module.
After switching off the engine, the after-run pump
always runs for 15 seconds or 3 minutes after the
engine has been switched off. If during this time
the switch-on temperature of 102 C (coolant
temperature) is reached at the thermostat of the
second fan stage, the after-run pump continues
to run and the coolant fan continues to run in the
after-run stage until the switch-off temperature of
91 C of the coolant at thermostat has been
reached. The maximum running time of the after-
run pump is 10 minutes.
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19-33


The control module for the after-run pump and coolant fan is installed
below the longmember (left side)

The thermostat is installed in the coolant return hose.
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19-34

After-run coolant pump, removing and
installing


Note:
The electrical coolant pump is located on the right side behind the
generator. - Remove noise insulation panel.
- Drain coolant page 19
-11
.

- Disconnect connection -1-.
- Disconnect both hoses -3- and -4- from pump.
- Unbolt pump from bracket -2-.
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