Over time, a car's air conditioning system will begin be less and less effective, until the day when you turn the knob and all it spits at you as you roast in the summer heat are tepid, warm gusts. You can fix this, but having your A/C recharged generally runs a few hundred bucks, and the do-it-yourself cans have bad reputations from years of dodgy ingredients.
If you like the classics and your car is pre-1994, you're faced with the even bigger bill of converting your system from the out-of-favor R12 Freon refrigerant to the current widespread standard , and that means hours of expensive shop labor to changeover a bunch of little rubber seals.
Naturally, people have tried to figure out shortcuts to save money during this process. Below are a few of the questions and myths on everyone's mind when faced with a hefty recharging bill or heftier conversion bill, and most are bad news for the wallet.
How much refrigerant leakage is normal?
An A/C system is not airtight, says Ward Atkinson, an air conditioning expert with the Society of Automotive Engineers. It can be nearly airtight, but refrigerant is always trying to push its way out and float away into the air. Refrigerant is a liquid when pressurized inside your car's A/C system, but it leaks out as a colorless gas. You won't see it or hear it when it happens.
R134a systems don't leak as much as the old systems did back in the R12 days, but the SAE says the average model year 2017 car leaks 0.41 ounces of refrigerant per year. It's a big improvement from 2001, when the European Union estimated the cars built that year leaked an average of 2.36 ounces per year.
Will it hurt to keep running an A/C system that blows warm air?
Yes. By the time you notice the system is blowing warm, it's already lost a lot of refrigerant. More importantly, refrigerant is mixed with a lubricating oil, needed to keep the A/C compressor operating smoothly, you're likely running the system too dry, which can eventually burn out the compressor by starving it of lubrication. Most refrigerants mix in an ultraviolet-sensitive dye, so while the refrigerant evaporates away, the oil/dye mixture leaks into the engine bay and leaves a traceable stain. Waving an ultraviolet light near the A/C lines will show where the leak is.
Will refitting my R12 system to use R134a refrigerant make it less effective?
Noticeably. That's the most accurate answer we can give you without knowing your car's particular cooling system, because they can vary a lot. R12 systems weren't designed for anything but R12, so if you're converting one to R134a, then you have to put in about 25 percent less refrigerant to account for R134a's higher operating pressure. R134a is a more efficient refrigerant pound for pound, says Griffiths, a Porsche air conditioning specialist, but you can't put as much in your car's A/C system as you could R12, so the end result is diminished cooling power.
Is it true that you when you get your A/C system recharged, you could be getting used refrigerant that was sucked out of the old car?
Yep, but there's nothing wrong with it. Shops will run the outgoing refrigerant through a recovery machine that scrubs it of contaminants like dirt, and it works just as well after it's clean. It doesn't go sour or lose effectiveness with age the way break fluid or coolant does.
So although you may be paying for 22 fluid ounces of “new” R134a, a portion of that could just be your old refrigerant cleaned up and resold back to you, some other car's old refrigerant. But you wouldn't know the difference or experience any downside if you didn't know about it.
Do they still make precious, icy-cold R12 Freon?
Manufacture was banned in most countries between 1996 and 2010, including in the U.S., but that doesn't mean it's gone. You can buy it, but the federal Clean Air Act says you have to be a certified technician. In practice, you can find it for sale by gearheads who hoard it. But then, if you're an amateur opening up the A/C system to recharge it, you're releasing whatever's left of the old refrigerant into the air, and that makes you the kind of jackass Captain Planet warned us about.
Also, people lie about what's in the can. They might say it's R12, but who really knows. Any decent A/C shop will be able to buy legit R12 for you and recharge your system the right way. “There's still plenty of virgin R12 around,” says Candido “Candy” Figueroa, of Miami's Auto A/C World. “It is very expensive, and we only use it on cars that are going to be judged.” Expect to spend at least $200-300 for a couple of cans and labor, although that's hundreds of dollars cheaper than converting to less-effective R134a.
Is it true those refill-it-yourself cans that say they're R12a or an R134a replacement are actually a cruddy old mix containing butane and propane?
Flammable hydrocarbons such as butane and propane are illegal for retrofitting into air conditioning systems because the EPA frowns on immolation. Brands such as Hot Shot and Freeze 12 have their own formulas that don't include butane or propane, but Figueroa isn't a fan of any DIY cans. They often have stop-leak mixed in with them, typically an additive of metallic filings or pellets that react to moisture and oxygen to gum up a leak in an A/C system. But the additive reacts with moisture anywhere in the system and not just as the leak point, so it can clog up a whole system. “Don't use it,” says Atkinson, as DIY cans also don't include any equipment to avoid venting refrigerant into the air.
Will your A/C system go kaput if you don't drain out all the old refrigerant first?
It could. R12 and R134a operate at different pressures, so mi too much of them creates a system operating at a weird pressure. Also, R12's mixed-in lubricant is mineral oil, and R134a's is a synthetic polyalkylene glycol (PAG) oil, and they don't play well together if combined. Any shop worth your money will vacuum out all the old R12 before converting the system and filling it with R134a.
Do you really need to replace the condenser and compressor when you convert an older car to R134a?
Sometimes. Certain cars' condensers, if made for R12, don't have the capacity needed to reduce high-side pressure when R134a is installed, says Atkinson. Usually, your old condenser will work fine with R134a. Your A/C shop can tell you if it won't. You do have to replace all the seals in the compressor, though. PAG oil can fail system seals and hoses designed for R12's mineral oil, so that's where most of your labor costs come from on a conversion to R134a.
Can you really use computer keyboard duster (R152a) to run your A/C system for cheap?
In theory—until it blows up and you're penciling in eyebrows over your face. R-152a is an extremely flammable hydrocarbon gas, just as propane is a hydrocarbon. Atkinson has a collection of photographs of dashboard fires from people who've recharged their non-R152a systems with R-152a, and he says because the blower is pushing air out the dashboard vents when things light up, the flames tend to get blown back at the passengers. OEMs are already searching for an R-134a replacement, and R-152a is one they're experimenting with, but it's not a good idea for your old R-12 or R-134a system.
After all, air conditioning is pointless if it sets you on fire, because then you're hotter than ever.