Various HVAC problems/AC radiator fan

1. Thought I had a vacuum leak- but- now air will go through each position (max, norm, bi-level, vent, heat, defrost) and comes out of the correct holes but only when I am moving above 25 mph or so. The faster I go the more the air moves. AND it can be controled to hot or cool.

What's wrong- blower motor? Can I test it with an ohm meter? Could it be a wire short in the dash?

2. I want to wire the fan on the radiator that kicks on when the AC is on to a switch on my dash. Can I just wire it through my fuse box? There is a white and a black wire coming directly off my fan. Can I assume the white is positive and black negative? With my AC not working, I don't know how to kick the fan on to test pos. and neg.

prl

I´ll answer 2 first, the easiest way to wire the aux. fan to a switch, is to find the thermal switch (lower left of the radiator) Looks like a 1 inch plug screwed into the radiator, with two wires coming out of it. Piggy back splice, two wires onto the wires near the connector for the thermal switch and run them back to a switch in the dash someplace. You can save a couple of feet of wire, by going into the harness, but it´s actually not worth the aggrivation. No need to have a power wire, one wire to the thermal switch is always hot when the ignition is in. Instead of the thermal switch turning on the aux. fan, when the temp. gets to high, you just bypass it with a switch and turn on the aux, when you want.
Answer for number 1. is a little more complicated. There is a resistor in the air box by the fan. Mine was burnt beyond recoginition. Fan for awhile had only high speed, then stopped all together. Also found the connector at the heater HVAC controls, under the radio, burnt some and the 25 amp fuse in the fuse block out. Probably gonna need a wiring diagram to troubleshoot, if it isn´t as simple as just the blower resistor.