Resonances just above the proton threshold in 30 S affect the 29 P(p, γ ) 30 S reaction under astrophysical conditions. The (p,γ )-reaction rate is currently determined indirectly and depends on the properties of the relevant resonances. We present here a method for finding the ratio between the proton and γ partial widths of resonances in 30 S. The widths are determined from the β2p-and βpγ -decay of 31 Ar, which is produced at the ISOLDE radioactive ion beam facility at the European research organization CERN. Experimental limits on the ratio between the proton and γ partial widths for astrophysical relevant levels in 30 S have been found for the first time. A level at 4689.2(24) keV is identified in the γ spectrum, and an upper limit on the p / γ ratio of 0.26 (95% C.L.) is found. In the two-proton spectrum two levels at 5227(3) keV and 5847(4) keV are identified. These levels were previously seen to γ decay and upper limits on the γ / p ratio of 0.5 and 9, respectively, (95% C.L.) are found, where the latter differs from previous calculations.