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Motor,  Apr 2003  by Weissler, Paul

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Service and repair options for today's sophisticated a/c systems are increasing. Our 2003 convention report provides the information you'll need to make the right choices.

"Reality Check 2003" was the theme of the Mobile Air Conditioning Society (MACS) Worldwide convention and trade show held recently in New Orleans. And it translated into real-world answers for technicians' tough service and diagnostic questions.

This report can't be a substitute for being there, of course. However, we can focus on some important a/c service questions that surfaced at the show and, hopefully, give you enough new information to help you do a better job. For example:

* Do a/c sealers really work, or are they possible trouble?

* Why am I having trouble finding leaks? Am I doing something wrong, or do I have the wrong equipment?

* Why do I hear about so many compressor failures, then repeat failures? What's really going wrong with them?

Should I stick with brand-new only?

* Is there one oil I can use in all R134a systems?

A/C Sealers

The short answer to the a/c sealer question is, they may work and, yes, they also may be some trouble. There are two types of sealers-stop-leak for perforation leaks and seal swelter for leaking O-rings and O-ring type gaskets. They're often combined in a single product.

MOTOR has recognized that the stop-leak type may seal small pinhole corrosion leaks in evaporator cores.

On older vehicles where evaporator replacement is a high-dollar job, that's appealing. Evaporator replacements typically cost $800 to $1000, while some can run as high as $3000.

Pinhole sealing is a valuable function. But there's no evidence that stop-leak will seal anything else with any reliability, whether it's cracked welds or a bad compressor shaft seal, or even severe pinhole leakage from the evaporator. Because the sealer works by reacting with moisture in ambient air, it also can produce clumps that restrict refrigerant flow, if there's enough moisture in the system. In addition, the seal sweller in some sealing products could distort some O-ring materials.

Several makers of refrigerant recycling equipment, including RTI, have reported problems with plugged solenoid valves. Skye has experienced problems with excessive swelling of 0ring seals. At this time, we've seen bulletins from Skye, RTI, Visteon, Ford, Delphi Harrison, Four Seasons and NAPA warning about voided warranties if there's evidence of sealer use.

Skye will be changing its machines' O-ring seals for resistance to swelling problems. It also has been working with AirSept (maker of a/c service kits) to develop a separator/filter for the inlet to the recycling machine. The AirSept device, which is in final testing, is intended to remove virtually all types of debris (including sealer clumps), plus oil, dye and seal swelter (typically an industrial alcohol such as methyl chloride). Eventually, the filter/separator, which connects to the inlet hose, will be marketed for all recycling machines.

In addition, Neutronics, maker of electronic refrigerant identifiers, introduced an R-12/R-134a systems identifier for stop-leak sealer. But it's based on inexpensive "mechanical" technology: Does anything in the refrigerant (e.g., sealer) plug a small, tortuous path that has been wetted with plain water? The identifier consists of a fixture attached to the highside service valve that holds a fitting with the small, twisty flow path, and a flowmeter at the outlet of the fixture. The technician watches for three minutes as the flowmeter reading rises, in part from water being pushed through, to a peak in about 60 seconds. A drop of more than 40% from that peak after another two minutes means the fitting has been restricted by sealer. The test fittings are discarded after use; other parts, including the flowmeter, can be cleaned. The amount of refrigerant loss is insignificant, and within EPA-legal guidelines for testing.

Even if you personally don't use sealers, out there in the real world they're being sold in high volume. Because some are promoted for preventive maintenance, they may well be in a customer's car. And although there are some sealers with labels for underhood application, don't bet on fInding one. So identifying systems with sealer not only helps you with a diagnosis (such as for restrictions and possible damage to the compressor), but also helps protect your recycling machine.

Protecting your recycling and other equipment with a filter/separator and/or identifier is one aspect of the sealer issue. Can you do anything with a system that has been restricted? The answer may be yes, if you can flush the system, particularly hoses, evaporator and condenser. But ordinary flushing agents won't work, and you still need an operable compressor.

Visteon's Reno Faruggia, who raised the sealers issue at last year's MACS convention, worked with suppliers to develop a flushing system to remove sealer from systems. Visteon selected RTI to introduce a new terpene flush and a continuous-loop air-- operated flushing machine to remove sealer from the evaporator, condenser and hoses, along with dirty oil and debris from compressor and desiccant bag failures. The flush and machine are in addition to the Bright Solutions terpene flush and the Cliplight machine that Visteon and Ford approved (and made available to dealers) before the sealer issue surfaced. RTI says you can use its new flush in a Cliplight machine. Or the Bright Solutions flush can be used (for other than sealer removal) in the new RTI machine.