Older unit may have pinched wires, to be lazy i will not advise here, pain to do with phone.
Search "fuse blows" here on IRV2 and you will find a lot of ways to troubleshoot.
You will need a volt/ohm meter and/or a test light.
One other poster made a "test light fuse " that i thought was a great idea, soldered wires to a blown fuse then connected them to a 12 volt bulb, when inserted where the fuse is blown it lights up, as wires are moved and the short is removed the light goes out, great idea!
Do some reading first, then get the tools and start hunting.
Tony & Lori
1989 Country Coach Savannah SE