As stated in the thread, both fans should come on together, at slow speed for 90°, high speed (which is really noisy and moves a lot of air) if you get to 100° or so.
You can test the fans by applying 12v to them using test leads: they will spark and the leads grow warm as you're pulling something like 10 Amps to power each fan. Seriously powerful. Don't touch them while they're moving. If nothing works, the fan motor has burned out: if only high speed works, the built-in resistor has burned out (the most usual failure).
The usual test for fan function, if you have aircon, is to start the car from cold with the aircon off: the fans should not spin up. Switching the aircon on (press the snowflake button) should start both fans at low speed.
If the fans check out OK by applying direct 12V but one doesn't work when attached to the fan control unit, then the control unit is probably faulty. I don't think VCDS picks up faults from this unit - I've just got mine and am waiting for the VCDS-Lite registration to come through, so I can't be sure.
You can test the fans by applying 12v to them using test leads: they will spark and the leads grow warm as you're pulling something like 10 Amps to power each fan. Seriously powerful. Don't touch them while they're moving. If nothing works, the fan motor has burned out: if only high speed works, the built-in resistor has burned out (the most usual failure).
The usual test for fan function, if you have aircon, is to start the car from cold with the aircon off: the fans should not spin up. Switching the aircon on (press the snowflake button) should start both fans at low speed.
If the fans check out OK by applying direct 12V but one doesn't work when attached to the fan control unit, then the control unit is probably faulty. I don't think VCDS picks up faults from this unit - I've just got mine and am waiting for the VCDS-Lite registration to come through, so I can't be sure.
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