You can check whether the coolant hoses are getting hot just by feeling them, though I suspect it's more likely that there is an issue in the control unit or motor where it is not opening the valve to allow the coolant to go round the matrix. This seems more likely.
2013 GT86 White, Bespoke TEIN Street Flex EDFC Active Pro, fully poly bushed, SPA rear lower arms. Injen Induction, TD EL manifold, Milltek over pipe, decatted, TD resonated exhaust and decat pipe. AP 4-pots BBK. TE37's, mega sound system.