Wipers and Heater only work occasionally

i'd have to say eitehr a bad ignition switch may be the problem or one of the fusible links that connect to the starter relay. without seeing this car this si a total shot in the dark. the pic i've included will give you some direction as to where things are.. thel links are smaller wires connected to larger ones you can test it with a test light by poking the wire to see if the light is dull on the one side. the other will be battery voltage. it cold have just a few strands connecting to drop the power down causing your problem.