I have a similar problem. Replaced the control module and the actuators and the actuators don't seem to do anything no matter what I set the controls to.

The common reason for that is that the controller has internal errors. You need to use a dealer or similar scan tool to check the climate control head for stored codes. It will also allow you to verify that the control head actually is functional. They can light up and seem to operate but not send control data to the actuators.

Mine turned out to be a bad ground circuit to the actuators and the blower motor. Ran new ground wires to each of them and they all started working.

That is always fun. They like to tie grounds together and then put the ground connection right in a spot that gets water/dirt/salt around it so it corrodes and fails.
That is one nice thing with the scan tool you can watch the control voltages. If you see say 12 volts on one side of the actuator and the same on the "ground" side, you know the ground is open.

Sadly mine is a 95 and is ODB1. No one has a scanner for it even if it did record that stuff. I found mine the old fashion way with a test light and on OHM meter... :-)

That same testing is how you find that issue on a 2018 so it isn't that old.... :-)
You might be surprised what a scan tool can pull on OBD I systems.
But you found it without one.
Good job.

If you know where I can get a scanner that would be awesome. Under certain conditions I get a check engine light and no one knows what the fault is.

On an OBD I you can pull trouble codes with a paperclip. Not all of them but if it's stored it should show up.
https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

As for getting a scan tool, how much do you want to spend? For a pretty good unit you can get something like an OTC Genisys with OBD I and II coverage for around 5-600.00 on Ebay.

Yeah, they taught us the paperclip trick in school. I would love something with a digital readout but not willing to spend over $100 for it. It's ok. I love that it makes me solve problems through troubleshooting, which is more challenging... (said no mechanic ever)... Hahaha..

That tool isn't one of the cheap ones. It is a full on real pro level device just not the latest and greatest, if you buy one with all the gadgets and latest updates you have a tool that covers just about every Domestic/Asian/European car/truck from the 80's through about 2012. It can do ABS, transmission, Scope, exhaust gas, and more. Not just reading the codes but showing live data, bi-directional controls, testing, and more.

As for troubleshooting. There are a lot of folks who believe in the "Test don't guess" methods.