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 R134a, 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.
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.
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 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.