Maybe make this a "Sticky"?
Does it run at all, or only on low? If it only runs on low it's the blower speed switch. If it doesn't run at all, the heater fuse or blower speed switch may be bad. If it runs on high only, the blower speed resistors are bad. If it runs on medium low, medium high but not high, it sounds like one of 3 things (since you said there's no power at the red wire connector at the relay I'm pretty sure this is your problem). I've found many times that the connector on the "fat" red wire from fusible link "A" on the starter solenoid gets corroded. Trace the red wire back from the relay until you find a connector. Pop the connector apart & visually check the terminals for corrosion, moisture or crud. Also check for voltage. If there's voltage, disconnect the "+" battery terminal & spray some contact cleaner in there, clean everything with a wire brush, lube it with contact lube & reconnect it. Then reconnect the "+" terminal & try the blower. If there's no voltage at the fusible link where it connects to the red wire, the link is bad. If there's power at the red wire on the relay & there's power at the blower high speed relay coil (orange wire) but not at the purple wire on the relay, the relay's bad. If the purple wire has power at the motor, the blower motor's bad or you have a bad motor ground.
Tommy