U r Correct phyre3 as the resistor pack failure is indicated by blower only working on high. Conversely, if the lower speeds work ok, but high speed is sluggish or wavering, the circuit is resistive.
I solved my wavering problem by replacing the blower motor relay. It had breached and spilled its oil all over the relay socket and was causing a high resistance circuit which prohibits the blower motor from getting the current flow or amperage it needs.
I flushed the socket with brake cleaner to get rid of the oil residue and then plugged the old relay back in and the high speed worked fine. I could have just left it that way but I went ahead and ordered a new relay.
The internal oil is there by design so less problems in the long run by using correct part. The relay is mounted above the glovebox on my 2004.
