I re-assembled my car & installed new ac harness, engine harness & lighting harness. When I turn on the fan the low & medium speeds worked but not high. I replaced the fan solenoid & it worked for a day then stopped working again. Anyone know what might be the problem? Did I blow the new solenoid? If I did what would be causing the solenoid to blow?

More than likely the fan isn't getting power in the high speed position. The relay gets 12 volts from the fused wire that comes from the horn relay on the firewall. This fused line goes to the relay contacts to run the fan. Think this is an orange wire. Has the fuse blown?
The relay coil is operated by a wire from the switch in the dash. Think ths is a blue wire. When you select high speed the relay is energized, closes, and the fan runs on high speed. Can you hear the relay closing? Guessing you may not be getting power from the dash switch.

At first I didn't know what to think so I bought a new relay & a new switch. I figured I'd replace the relay first since that was easier than taking the dash apart. I replaced the relay & it worked fine so I assumed the relay was bad. Then the next day it stopped working again. I don't hear the relay clicking like I did when it was working so either it's not getting power or the relay is blown. What's the best way to check the fan relay to tell whether it's good or not? I really don't want to spend another $20.00. if it is bad, what would cause it to blow?

Double check the wire colors on the relay, but I'm remembering them as:
Orange = fused 12 volts from the horn relay. Goes to a relay contact.
Purple = Output to fan. It's the other normally open contact. Gets power from the orange when the relay is closed.
Black = ground for the relay coil.
Dark Blue = positive side of relay coil. Comes from the dash switch when high is selected.

Should always have 12 volts to ground on the fused orange wire.

Should have 12 volts to ground on the dark blue wire when the dash switch is in high position.

Check voltage at these 2 points to see if it is present. If you are missing it on the dark blue wire, the relay won't close. Double check the colors I mentioned. I don't have a schematic in front of me and working off the top of my head. If the colors are correct jumping orange to blue will close the relay and turn on the fan.

I'll check that one night this week. Thanks for your help! If I figure it out I'll let you know.

I found the problem. The fuse holder that came with the new harness was defective. I splice in a new one & it works fine. Thanks for your help!