Used to go threw lots of them switches. I think switches improved a few years back. Are you getting OEM switches that haven't been in bin for yearsIJ I forget what year they went away from very large rubber plug for fan switch wires but we had to cut them off and install individial connectors for the large rubber plug held heat in so well that things would burn up. Installing individual connectors would allow heat from voltage drop to be displaced without burning anything up. Don't think your fan is bad for that should blow fuze. You may want to service air filters and have a look at evaporator for if pluging up it may cause fan to pull to heavy. Good luck