On mine the aux fans will run slowly under some conditions...say it is moderately warm out 80*F and I come to a stop at a light...then the fans will kick on and the longer I idle the faster they will turn but they don't really go all that fast unless the conditions are extreme (pressure or temps). But, when I turn the system on and it is not really all that hot out the aux fans don't turn at all and they shouldn't turn. They are meant as a means of extra air cooling of the condensor not to provide constant airflow whenever the A/C is on. I think you can monitor the current to the fan motor from the console.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz