I have recently replaced the blower motor and the heater core in my 69 Convert, Non AC. (Both of those jobs SUCK, BTW!!)

Anyway, I am only getting the fan to operate in one tiny little section on the slide control. (High) Do I most likely have a bad fan switch, or would it be more likely the resistor in heater box plenum?

As Always, thanks!

Resistor. High speed bypasses the resistors and feeds 12V directly to the fan. Resistors almost never go bad (unless they melted because the fan wasn't blowing air over them. Check the connector on top of the inner heater box. Make sure the harness conector is on the terminals all the way. If it's on all the way check continuity between the three terminals on the top. You should be able to measure continuity from the two that are inline with each other to the third terminal that is offset from the other two. If you can get a reading then check for voltage at the terminals that plug into the reisistors.

There should be a light blue wire, a yellow wire and an orange wire on the blower motor resistor. Orange is out to the motor, light blue is slow speed input from the switch and yellow is medium input from the switch. Check for voltages on the yellow and light blue while operating the fan switch to see if your getting power to the resistors from the switch.

Great info, Mark. Thanks a million!

Mark-

Thanks for the help = I wiggled the connector at the resistor and now I have 3 speeds on the fan again!!

While I was digging around, I found these wires on the same harness as the one that goes to the resistor....any idea what they are for??

http://img20.photobucket.com/albums/v61/gort69/69%20Camaro/DSCN2180.jpg

The bottom black one, is for the glove box light. The white one is familier, but I cannot place it right now. Clock maybe? Or a direct plug into the fuse panel?

IF there is a guage cluster harness, yellow also could be low fuel warning light.

graemlins/beers.gif

Just what is the purpose of the Heater Resistor? A thermostat to control heat? That almost seems like too much technology for a 35 year old car!

The heater resister is what drops the voltage so the motor turns slower at the lower speed settings. Since dropping voltage creates heat, they always put it inside the heater box so the airflow will keep it cool.

OK, that makes sense.

Thank you