It's starting to get cold in Michigan and I need some heat the enjoy the drive. The heater motor fan at full blast does not seem to run very fast. Does the resistor affect full speed, or should I replace the fan motor.

In some of the vettes the high heater blower has it's own separate resistor.  Not sure about the 75.

I dont want to stomp on your thread, but mine has only high speed on the fan. I replaced the fan switch without positive results. Maybe I will get my answer too.

The high speed runs off of a dedicated relay...no resistors for that. The relay is normally attached to the A/C plenum under the hood, close to the resistor block for the fan motor.
If the fan is running with the switch on High, the relay is working. If it seems the fan is slow, the fan itself is most likely the problem.
If you only have High speed, the problem is most likely the resistor block, or possibly a fuse.

What the apple said, ya, ah huh.

One thing about my vehicle, it does not have AC. I do not see a relay.

The contacts on the resistor are bad about getting corroded.  Pull them off and clean both sides of the solderless connectors and plug back in, that may be a quick fix to your problem.  I also had to work on my relay which was mounted on the firewall.  The points had "fused" together and would stick, not allowing the relay to return to the "off" position.  A little 200 grit abrasive paper slid between the points a few times and the relay was working again. Ill eventyally have to replace it but its been working after that "bubba" fix for 2 years.  If anyone needs pics of where the relay and resistors are located give a shout, I have pics of where they are on an 82 and think they are pretty much in the same place on most sharks. Crossfire19822009-10-31 06:52:51

Ok, please send pics.

OK, here is a pic of the blower resistor and relay.  You may have to move the wiring harness a bit to get to the base of the resistor but its not difficult to get to really  The resistor itself is inside of the air plenum.  The resistor is quite long and you can see only the base of it until you remove the screws and pull it out of the plenum in order to make sure the wire coils which make up the resistor are intact and not broken.

Thanks for the photo, but my vehicle does not have AC

I think non AC vehicles do not have a relay and is the resistor in the same place?