I highly recommend people who live in hot environments to keep a spare capacitor on hand. Even if you know how to fix it, if the AC dies when your local HVAC supply store is closed (eg not between 7am-7pm Monday through Saturday usually) you’re either stuck paying out the nose to a contractor who has one on hand during emergency hours or you’re sweating it out waiting for the store to open. While they are readily available components that consumers can purchase, they aren’t things that Walmart carries. But HVAC supply shops will sell them to you, you don’t need to be licensed or anything to buy them. You can also just get them on Amazon, likely for cheaper than the HVAC supply shop will sell them to you.
It really is an easy repair. Needs a screwdriver and knowledge enough to shut off the electricity to touch the wires. According to code every one of these condenser units outside has a disconnect right there so you don’t even need to turn off the power at the breaker box. Just pull that disconnect, open up your outdoor condenser unit, snap a pic of the specs on the capacitor (it’s the only thing that looks like a soda can) and order one off Amazon and stash it somewhere. It’s a tiny part. It will take like 5 minutes max and save you several hundred bucks and a lot of sweat eventually.
FWIW, when ac dies it’s usually in this order of root causes:
Float switch: your condensate drain line got clogged because it just does and you need to clear it. You can proactively prevent this by pouring bleach or vinegar down the line periodically (what clogs it is usually some sort of gnarly plant like growth from all the moisture) or if it’s clogged you need to clear it. The hvac guys will charge you 300 bucks to blow pressurized air through the pipe or you can literally just duct tape a wet shop vac to the thing and suck it out yourself. Attachments can be purchased on Amazon for reasonable price.
A capacitor issue is the second most common. If it ain’t the float switch almost always it’s the capacitor. You can increase your capacitor longevity and also decrease your electric bill by changing your air filter regularly but also hosing down the outside condenser coils every few months or so. Almost everyone knows about the air filter but few people know about hosing down the coils. This makes a HUGE difference. We are talking like 20-30% of your electric bill in hot climates if you don’t do it. Just take a hose and spray downward on the grates and get all that dust and dead grass from mowing out of there. You won’t hurt the thing. Why does this help? Well, it’s better to think of AC not as adding cool air. There’s no such thing as adding cool air. Only removal of heat. How does heat get removed out of your house? Through that condenser unit. If those grates are clogged up the heat cannot escape and the unit must work harder to do less effective job. So keep those coils clean.
Everything else after that is way less common. Yeah compressors do die. Motors die. Refrigerant leaks. Computer components die. Thermostats fail. However it’s very rare that the issue is something other than these two things in comparison. Like probably 80% of all HVAC residential calls are probably the above two things I mentioned.