have a 68 camaro and when on a/c i can only get low speeds on fan. the fuse above the dist. is good----which i understand is the high speed fuse. the fan motor was replaced recently by someone else and i would appreciate some troubleshooting tips.

Selection of MAX A/C should give high blower speed, maybe.

If the fan runs in any speed, its fine, there is only one set of windings in the motor, the blower motor resistor controls the speed by droping the voltage the motor sees. Is the relay on the evaporator housing picking up when you put the switch in high speed? If not check the ground for it.

it is plugged in....mounted on the plastic housing thou. is there supposed to be a ground wire to the chasis from it??

Yep, black wire to a screw on the firewall next to where the big plug of wires next to the evaporator housing goes thru to the interior of the car.

thanks for the info