My fan is hooked up so it's always on. Just recently I had a problem and my fan wouldn't come on at all, I replaced the relay and that was it. Now yesterday I realized it's not coming on again. What could be my problem? 1987 Iroc-Z 305 5.0 LB9

check your wiring were the big connector is I had my fans stop working, and spend like 2 days looking over everything, and finally realized that the ground wire in the connector was fried.

How did you wire it?
Little thought of mine, it is better to have it hooked up to a fan switch, these fans aren't meant to run constant, and at higher speeds don't do anything even if they are running.

Are you getting power to your switch, to the relay, thru the relay.
Do you get power to the fan?
You can jump the fan to the bat to make sure it's still working. If you have a factory or factory replacement fan, make sure you hook it up right if you jump it.
Some after market fans, you can wire them either way, just reverses direction, it will fry a factory fan.