If you do change the transformer yourself. Set the thermostat to system off fan auto. Turn power on then change the fan to on. Then if it stays running turn the system to cool, if it stays running your good(unless you check heat operation, good techs always do��). If it goes off when you switch too cool then it’s most likely in your 2 wire going to the condensing unit or the contractor, in that case hopefully you put the inline fuse in or else it’s a second transformer. But fear not your compressor should be fine, compressors don’t take out transformers. Or at least I haven’t seen it yet.