See post #8.

The stock wiring is not adequate for high fan on the low fan circuit.

But it can be made to be ....

The resistors have a long life and the new ones are open coil, so they last longer than the originals.

What taxes the resistor is the fan motors start to get dirty/rustted bearings and worn brushes, thereby drawing over spec Amps..the R15 does not like that ....the other is the connections start to conduct poorly b/c of heat fatique...so, again, tha R15 gets a shortened life.

__________________
A Dalton