My central AC is making this weird gurgling, bubbling noise, almost like a coffee pot perking. It’s still cooling, but the sound is totally new and a little unsettling. I’ve checked the filter and it looks fine. Is this something I should be seriously worried about?

The coffee pot sound is a great description! We've heard that one before. When an AC makes a gurgling or bubbling noise, it's usually a sign of one of two things, and you're right, it's probably not a DIY fix you want to take on. To answer what the noise is:

1. You're low on refrigerant. This can cause the cooling coil to freeze up. As the ice melts, you get that weird noise as the air and water mix. A low refrigerant level means you have a leak somewhere, and an AC technician needs to find and fix it properly. Just topping it off does not fix anything.
2. Air or moisture in the system. If air gets into the refrigerant lines, it can cause those sounds. This is a big no-no for the long-term health of your unit.

Either way, you want a pro to check it out. They can hook up their gauges and diagnose the problem in minutes. Trying to DIY with refrigerant is a bad idea boss. You're dealing with pressurized gas, and it's a regulated substance. Better to have someone with the right gear and know-how take a look before it turns into a bigger, more expensive problem.