For $29/mo, we provide access to advanced level technicians who will answer your questions on any Macbook board related matter to the best of their knowledge promptly & walk you through how to solve your problem so you can deliver a working board to your customer.
(After trying new fan) Check that the fan plug is sitting in the socket correctly as if pin 2/3 not connecting it may run full check that the socket does not have broken pins 2 or 3 to the board. Check resistance of R6061 (100k), R6065 (47k), R6060 (47k) (page 45 of schematic) check continuity and shorts to ground in this area - could be Q6060 not controlling properly. Had very similar problem (and ASD results) on an iMac recently and it was one of those resistors that someone had knocked off the board.