Absorption and free-jet action spectroscopy of states in the region of four quanta of C-H stretching of acetylene (C2H2) around 12 676 cm-1 were studied. Rovibrational excitation combined with 243.135 nm promotion of C2H2 molecules to the upper electronic trans-bent states, A (1)A(u)/B B-1(u), and H photofragment ionization generated action spectra measuring the H yield as a function of the excitation wavelength. The findings show that the (1030(0)0(0)) IR bright state of the third C-H stretch overtone has a smaller photodissociation cross section than the (1214(0)0(0)) combination band containing trans-bend mode excitation and lying in its vicinity, due to a favorable Franck-Condon factor for the latter. Certain line pairs accessing similar J(') levels of the (1030(0)0(0)) state show anomalous intensities in the action spectrum, with P transitions excessively enhanced over R transitions. This implies enormous dissociation efficacy as a consequence of Coriolis-type local resonances with nearby states of another band and due to the overlap of the P transitions with another band.