I have replaced all three fan relays on my 2004 impala. Fans still do not come on. I put voltage directly on fans and they will run. What else could be wrong?

They should only come on if engine temp gets to high or if ac is turned on at an idle.

The radiator could be stopped up not letting sensor read correctly. With A digital thermometer you can che k temp of top hose and lower hose at running temp. If not drastically different no blockage.

Hey guys, my son has a 2003 Impala (3400). The relays going to the fan keeps blowing. We replaced the fans (they were bad) and still nothing. We ran a direct wire (fans work)...then we ran power to the temp control sensor they engaged but would not shut off (even when power was removed. We checked power to the fuse box everything has power but only one side of the box's relay (fan 3) the momentary switch engaged.....could the fuse box be shorted out. I'm desperate, got the fan hooked up on a toggle to keep it from over heating.....please if anyone has any ideas.