Another FCM failure thread


Veteran Member
Sep 29, 2011
Brighton - Oshawa Ontario
15 Jetta TDI
Have some Fan / AC issues with my Jetta and Golf . Nothing better than spending a few hours in the garage a few nights in a row .. my wife might not think the same.
Pretty sure I've narrowed the issues to the FCM on both cars but could use other eyes / opinions on it.
Wife's car
Observations :
Spring Check up - AC was working , but big fan seized
Replaced big fan
Month goes by and it gets warmer , and the wife tells me AC is nice and cold when moving and on the highway . Stops and blows warm when at a stop light or waiting in traffic.
Do the thermo sensor test with key off jumpered low speed works great , jumper high speed with key on the fans start to move , then click off .

Question - Is this going to be the FCM? :confused::confused:

My car so spring check up was put off - :D
Observations :
AC button pressed no fans and no compressor engagement.
Resistance fine on compressor
All fuses are fine
thermo sensor test with key off jumped low speed works great , jumper high speed with key on and nothing
Pulled the FCM and pulled it apart after seeing the connection pins all corroded.

Obviously this is going to be an FCM issue. :eek:

Needless to say my concern as the hotter weather is approaching , is engine cooling , and AC as a secondary .
Last edited:


Veteran Member
Sep 30, 2010
Kitchener, Ontario Canada
2015 Sportwagen 6M, 2006 Golf GLS TDI (sold)
Based on the amount of current passed through the FCM and how corroded yours is, I'd replace it for safety, even if it weren't the cause. Mine shorted and caused a heluva mess of melted harnesses.