Not sure if the 2014 ACE uses the BCC cabinet from RV Custom Products (located in Engine Bay Driver side; front). If yes then the fuse for mirrors is F5 and mirror heaters is F12; connected through terminal strip P5 cct board in the BCC. Schematic attached......right side accessory relay controlled.
If 2014 does not use BCC any more (2013 does), then I don't know.
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