Just like the title says, when the ignition is on, the fans are on. This is my boss's gf's car. He took it to a local mechanic, and pretty much I know that the PCM was replaced, any ideas?

 

Gotta love it when shops just throw expensive parts at the problem.

I would unplug the fan switch with the car running and see if fans turn off. If they do, the fan switch needs replacing, which is cheap and easy. I believe it is a grey plug, connected to a brown plastic sensor in the thermostat housing, under the throttle body.

You can also try unplugging the pressure sensor in the condenser with the car running, and see if that kills the A/C and fans. If it does, it probably means there is something wrong electrically with the A/C system. However, unplugging this sensor should kill the A/C and fans should the fault lie in that system. It should be the only plug going into the top of the silver canister located towards the passenger side of the front bumper. You can see it from the top, when you pop the hood. You should be able to leave it disconnected without any issues, until you get the issue sorted out.

I assume the fans are on 24/7 with the ignition on, but the engine not running?

 

I unplugged the switch at the thermostat. I've got ground on both wires (black and green) with it unplugged and the ignition on, and the a/c panel completely off. The fans do keep running while its unplugged. I've also got ground on the green wire at the radiator fan control module behind the glovebox. (Even with the key off)... I've got continuity to ground at both places, with, or without the key on.

 

Hmm.

Was there anything done recently that might have caused a bundle of wires to get smashed? No random wires jammed under the battery tray, or something like that?

This one sounds like it might be brutal to diagnose...