Ban the Can: Injecting 134a Into Your A/C May Do More Harm Than Good

Periodic maintenance by a certified HVAC technician is the best way to make sure the air conditioner is holding its refrigerant charge. But what if you’re on the road and all that’s blowing through the vents is warm air?

It’s tempting to go to an auto parts store and buy a one-pound can of R134a, the kind with a hose on it that you can hook up to charge the system.

Don’t do it, says Frank Burrow, warranty and product support manager at Red Dot Corp. Based in Seattle, Red Dot makes heating and air-conditioning systems, components, and replacement parts for heavy trucks and other commercial vehicles. The company offers OEM-quality, all-makes replacement parts through more than 175 distributors in the United States and Canada.

“We see it a lot this time of year,” says Burrow. “A driver assumes the system has lost refrigerant charge because the air conditioner isn’t as effective as he’d like it to be. He goes to the auto parts store figuring to shoot some juice.”

“Shooting juice”—injecting R-134a from a can into the A/C system—may do more harm than good, Burrow says.

Auto parts retailers typically carry three varieties of canned refrigerant: R-134a with oil for the compressor; R-134a with oil and sealant; and straight R-134a. Each can be detrimental to your air conditioner.

For example, the oil mixed with R-134a may not match the compressor’s original PAG or ester oil specification. “If the compressor lunges, the manufacturer will analyze the oil for its type and viscosity,” Burrow says. “If it detects an oil that’s different from the original, the warranty is null and void.”

More troublesome is R-134a with sealant. As it circulates through the system, the sealant will encounter a leak and solidify when it contacts outside air. The problem is, sealant also can collect inside valves and tubes, clogging them up. Furthermore, A/C technicians may refuse to work on your vehicle if their refrigerant identifiers detect sealant because it can harm refrigerant recovery and recycling equipment.

So why not use a one-pound can of straight R-134a? “First, you don’t know if you need one pound of refrigerant to replenish your A/C system or some other amount,” says Burrow. “Second, if your system is losing refrigerant charge, you should see a qualified A/C service technician. He has the expertise and equipment to keep your system working properly.”

Servicing your truck’s air conditioner is not a do-it-yourself job, concludes Burrows. “What seems like a quick fix really is an invitation to an expensive, time-consuming repair job.”