No Substitutes

SSGM: What should technicians watch for in R-12 replacement service?

Farrugia: “Contamination is a big issue right now, because with R-12 being depleted sometime this year, many people are going to be looking for alternates to R-12. OEM’s will only endorse R-12 or R-134a in automotive air conditioning systems, and the real dangers of land refrigerants or refrigerants that contain flammables are firstly, they will contaminate your equipment. And once your equipment on the recovery end gets contaminated, any vehicle that gets serviced after that will also be contaminated. It’s kind of like a virus.

SSGM: We’ve heard of propane and butane as refrigerants.

Farrugia: The issue with flammables is that as the flammable refrigerant leaks into the passenger compartment due to a small leak in the evaporator, it could be potentially dangerous to a person who lights a cigarette or generates any sort of spark that has contact with it. For this reason, none of the OEM’s will endorse blends, or any refrigerant that contains a flammable material.

SSGM: So it’s not just Visteon.

Farrugia: Oh it’s all of them. It’s DaimlerChrysler, General Motors, all the import car manufacturers. They only endorse R-12 for R-12 systems, R-134a for any R-12 systems that have been retrofitted, or R-134a for any system that has been designed for R-134a.

SSGM: Are there true drop-in replacements?

Farrugia: No. The only recommended replacement is R-134a retrofit, and that’s where you have to change the fittings, the oil, and then the refrigerant, and, in some cases, a special high-pressure cut-out switch, called the refrigerant containment switch. Since R-134a operates at slightly higher pressures than R-12, in order to keep your system from venting to the atmosphere due to high pressure, it has a switch that monitors the high pressure. It will shut off the compressor.

SSGM: That’s an electrical switch that declutches the compressor?

Farrugia: Yes. The switch is mounted in the discharge hose of the system or on the discharge side and when it sees a pressure from anywhere of 425 to, say, 475 (psi) it can shut off the A/C system.

SSGM: At the higher operating pressures, is there any risk that the R-134a will find a weakness in a retrofitted R-12 system that can cause trouble elsewhere? Is the pressure so much higher that a potential weak spot in a converted R-12 system would then rupture or then cause a leak?

Farrugia: No, most of those components are designed to handle 500 to 600 psi. We’ve never seen it. The potential may be there, but we’ve never seen it. I imagine that if there is a very weak spot in the condenser under those high pressures, it will pop a pinhole or create a leak, but I’ve never seen a system blow up due to pressure on the high side.

SSGM: How about blends?

Farrugia: About blends, they’re very unstable because they blend different refrigerants together. When a system is sitting statically, like in a parking lot without the engine running, those different chemicals separate, so the R-12 will sit somewhere in your vehicle and the R-22 might be sitting somewhere else. And then when you first start the vehicle there’s no telling what kinds of initial pressures you’re going to have. It could be extremely high. SSGM