If both A/C and heater are turned off the blower should not run at all. Have you replaced the vacuum switch behind the push buttons? Some of them are wired different than others. I know when I rebuilt my 68 Charger, I bought a new switch that ran when ever the ignition switch was on. It is PN: 3502126. I'm not sure just what that switch was made for but I'm guessing that is what you have in your car. I have 6 different switches that most do something a little different that others but that one is the only one I tested that runs all the time. The one I have in my car now runs on low if I push the heat or A/C button even with the fan turned off. It is not supposed to but I'm ok with it. Don't let anyone tell you they are all the same just because they look the same.