When I bought my first car over ten years ago – a mid-90s Honda – the AC wasn’t so great. This really didn’t bother me as I was just excited to have a car, but as other stuff hit the fan and I started learning to work on the car, I eventually realized I could use one of those “AC recharge kits” you find at auto parts stores. I was nervous working with the little can under pressure, but it all worked out, and my AC was improved. Cool!
Years passed and the AC started petering out again, so what did I do? Got myself another recharge can and loaded it into the AC system. I was driving down I-25 in the summer, had the AC on, cruisin’, when suddenly I heard a massive THUNK and the car shook. Scared the hell out of me. What had just happened?
I eventually realized this thunk only happened when the AC was on. I did some research and bought an AC manifold gauge to check the low and high pressure on the system. It turned out that the high side was well over what it should have been. I had played the dumbass card and overcharged my AC system. The thunk was the security feature on the compressor forcefully shutting itself off to avoid internal damage.
And that, my friends, is why you never use “recharge” kits from auto parts stores!
(To be fair, since my system was leaking, the thunk went away, but mother nature has probably not forgiven me!)
The AC system is not something you simply “recharge” with a “kit”. It requires a specific amount of refrigerant to work properly, which is not something you can measure very precisely using cans sized to a particular standard. And just because your AC isn’t cooling very well, doesn’t mean it’s low on refrigerant. I’m no expert on this stuff, but when I studied up on it (a long time ago) I was kind of amazed at how much science went into the system. There’s only a few key components, but they aren’t necessarily easy to diagnose.
But “kits” sell. Who doesn’t want to save a little money and get their AC going nice and cold, eh? Eh?
I’ve always been nervous around those cans. Pressure just…I’ve never been a fan of pressure. I didn’t have impact tools for the longest time because I didn’t want to deal with an air compressor. Ten years passed and suddenly lithium-ion batteries powered most consumer impact tools, and then I was in the market for one! (Makes things so much easier!)
I’ve had friends and family with AC issues, and I’ve wanted to help them, often jumping into DIY mode and wondering if a good old can of R134a would do the trick…until I remember all the crazy charts and remember how stupid I am when it comes to the AC system. A few years back, my dad’s car was dead empty (no pressure on the high side!), but he got the wrong can (the little die ones, for finding leaks), and I really didn’t know how to measure capacity and all that. Plus, that thing had been leaking for years. I’ve been guilty of this too, but why are humans so quick to pursue the cheap fix?
For all the DIY I do on my car, I feel the AC system is something I simply don’t want to mess with. It occurs to me that I could probably get rid of my AC manifold gauge and be none the worse off, since there’s really not much you can do with it anyway (I’m trying to find tools that I’m not going to regret getting rid of. It’s hard. So hard! First world problems…)
I do all sorts of crap on the suspension, but I really don’t care to touch that AC system. You’ve got to know your limits.