The practice of solvent flushing a Refrigeration or Air Conditioning system has never been an acceptable method for treating a compressor burnout. Even in the days when R-11 was plentiful at about a buck a pound; flushing with R-11 caused serious problems.

I once sent out a new Service Tech to purge, evacuate and prepare a rebuilt compressor for start up on an old 25 ton system. This Tech was a rising star in the company having graduated with high honors from a top Refrigeration Trade School. He loaded the system up with about 10-15 lbs of R-11 backed with a bottle of nitrogen. After a few hours, the Tech called into the office complaining that his vacuum pump was not pulling down very well. I went out to the job site to assist. I arrived with the notion of a leak somewhere in the new connections. After the Tech explained to me everything he had done, I knew we were in for a long night.

Loading the system with R-11 turned into a nightmare. The solvent became trapped at low points in the piping. Every bend, nook and cavity in the piping contain small amounts of liquid R-11. Attempts to blow out the R-11 with nitrogen did not work. We connected two vacuum pumps and let'em run overnight. The residual R-11 was difficult, if not impossible, to completely boil off.

Recently, a few Chemical distributors have introduced [new] flushing solvents to internally clean piping. I bracket the word "new" here to bare out a half truth. These solvents have actually been around since the last supper. The only thing "new" is the intended application, "your next compressor burnout".

The solvent bottles are painted with extravagant claims many of which categorically are untrue.

………….leaves no residue

Physically, these solvents have a substantially higher boiling point than R-11, and we could not get the solvent to phase into a gaseous state under high vacuum. Another negative is the oily texture of the solvent which imparted a thin film coating to all our glassware. It was clear-cut that large quantities of solvent would remain in any system so treated.

.…. ……Neutralizes acid

We investigated the general chemistry of the solvents. The solvents all had an acid number. Not a good sign, but not an unexpected result, since solvents which best dissolve oil must have an acidic ionic character.

……….non hydroscopic

A readily identified compound in the solvent base uncovered Acetone. You can’t find too many compounds more hydroscopic than Acetone. Water adsorption from short term exposure to the atmosphere is faster and greater with Acetone than with a POE or PAG lubricant.

……….will not contaminate oil

Now here is a direct contradiction to the top claim. If the product does not leave a residue why would there be concern for oil contamination. It is because the solvents are polar and will integrate completely with oil. The viscosity of Oil summarily degrades with solvent contamination.

I will state for the record some nice attributes of these solvents. They all performed exceptionally well for cleaning and degreasing. No boner to pick here on effectiveness, the solvents removed grease, dirt and dyes. We also observed good softening action on my barbecue grill. By all measures of solvency testing, we award the high hard one, a letter grade of "A".

When marketing a cleaning product be aware of advertisements which strike a psychological chord. The use of catch phrases which stress the dangers of unclean conditions are most effective.

"I don’t want you liven in no roaches."

Certainly the marketers of the flushing agents don’t want you liven with the carbon, sludge, acids and other evil demons left over from a burned out compressor.

We live in a dirty world and we need:

"a white tornado that’s stronger than dirt with a clean that sparkles and a shine that lasts"

The psychic virtues of sanitary stimuli are powerful selling points and we are all culpable to some degree. In the case of solvent flushing a system, the science of proper Refrigeration practice is violated, but talk'in dirty can persuade the unconscious mind.

Assume the missionary position and brace yourself for the ride. The best way to flush a system is the old fashion way. Install a suction and liquid line drier, pull a deep vacuum, fully charge the machine and energize. All the carbon, sludge, acid and other evils will be power flushed into the filter cores. Let all the natural juices flow with each compressor stroke. The Refrigeration System is a continuous self cleaning apparatus. Engaging in lengthy foreplay with a solvent flush consumes useless time, expense and energy.

As I stated earlier these solvents are excellent cleaner/degreasers. My only objection is with their proposed application. I believe there is a place in our industry for top quality solvents as long as they are used on the outside of the cooling equipment.

Remember, R-11 was the most effective cleaning compound ever made. Industries world wide relied on R-11 for cleaning and degreasing in just about every manufacturing sector. R-11 was the "perfect solvent", electrically nonconductive, non flammable, non combustible, quick evaporating leaving no residue. To date, no one has been able to duplicate or find an equal replacement solvent for R-11. The company that does will get layed with billions.