My heater fan sputtered on/off on any fan setting for a few weeks and then died completely. It did not even work at the highest speed. After troubleshooting the fan motor was assessed as good as well as the fan fuse, fuse block and fan speed control switch. The problem was the poor conductivity of the spade contacts on the resistor pack (p/n 52454908). This is mounted behind the glove box into the plenum of the blower case. After many years the contacts had become overly oxidized which I suspect is due to not being hermetically sealed from the plenum (resistor) side. Rather than spring for an expensive new resistor pack, I fashioned a sanding block from a thin piece of wood and burnished the spade contacts and sprayed them with contact cleaner. At that point I could easily measure resistances ranging from 2 ohms and up across various contacts. With the resistor pack put back in place, the heater fan came roaring back and blows out luscious warm heat on all fan settings. Car is now ready for winter.