I've read through every fan problem on this site and have yet to find the answer I need, mostly because I have no idea what I'm doing when it comes to electric entities. Got a dual fan setup on an 88 GTA with the 5.7. First thing I thought of was the fan switch, which I replaced a few years back with one from Hypertech. But if that went bad, it wouldn't cause both fans to be completely off at all times, would it? By the way, it is plugged in. Then I did the ALDL thing and only the drivers side fan comes on. Not sure if both should come on or what, but I guess it's a good thing that even one turns on. I have read that there are two relays, but I have no idea how to use a voltmeter to check if they are good or not. If someone could patiently walk me through this, it would be much appreciated as it is my daily driver, and need it ready for work on Monday. Thanks in advance.

I have a voltmeter, if I need it to check the relays.

 

So the car is overheating? To test the passenger side fan start engine and turn a/c on high after couple minutes it should kick on.

 

It is easier to switch relays out to see. Just don't mess with your fuel pump relay.