The Atlantic Meridional Overturning Circulation (AMOC) is considered to be a tipping element in the Earth System with multiple stable states. Here, we investigate the multiple equilibria window of the AMOC within a coupled ocean circulation-carbon cycle box model. We show that adding couplings between the ocean circulation and the carbon cycle model affects the multiple equilibria window of the AMOC. Increasing the total carbon content of the system will widen the multiple equilibria window of the AMOC, since higher atmospheric pCO2 values are accompanied by stronger freshwater forcing over the Atlantic ocean which acts to increase the window. Our results suggest that future changes in the marine carbon cycle can influence AMOC stability in future climates.