OK

Two possibles ..
One is both fans are bad and you have only noticed the problem when the last one went out..meaning they most likely did not crap at the same time..

Second is you have a bad/poor connection between the R15 terminals and the fan motors.. The motors have a common plug for both, so you may want to check that plug
it is tucked in behind the fan cage and hard to get to, but look around for it.

Also make sure the wires are tight on the R15 where you jumpered 12 V. pos to.
If you put a test lamp at the terminal oppisite the one you are jumping to, that will confirm you have a good jumper feed.

My guess is bad fan motors.

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A Dalton