Ok you said you have low speed, Eahc resister pack also has a relay, have you cheked those? Ok lets assume they are good, do to the fact you said you have low speed, I beleive the resiter pack on the left side, is for the low speed, switch the plugs around, see if the blower is now only on high speed, if so, you know the one on the drivers side is bad.Honestly Tom it can only be either one of those resister packs, or one of those relays.