1968 non air SS 350. Only getting one speed when I operate the heater fan switch. Replaced the fan switch and resistor unit (in the heater duct box). Wiring seems ok at the resistor and switch. Read other forum comments regarding an in line fuse on air equipped, but don't see one on my non air. I get continuity & different ohm readings ok at the heater switch. Any suggestions?
Must be a wiring or connector issue - the separate fused feed wire was only used on A/C units, for the high blower speed.