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Hi cant change speed on the blower
It stays on high all the time
TIA
Randy

My 67 manual says the speed switch goes to a couple resistors
(no doubt located in the air stream) and the motor direct. I
would unplug the resistors and see if the motor stays on high,
if so the problem may be in the switch.

HOWEVER, I have seen variations where a relay is added, that
the switch activates for direct battery connection on high. If
you have this, the relay could be stuck closed.
good luck, Bruce Roe

The blower motor resistor is installed into the top of the heater box under the hood, make sure everthing looks good on that. It will have a few sections of coiled wire, make sure none of the wires or solder joints are broken. The system is pretty foolproof, so as long as the blower speed switch is moving correctly, it's usually a wire has come loose or the resistor is failed in some way.