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Acetone For Flushing Agent?

69Sixpackbee on Tue January 15, 2008 12:39 PM User is offline

Year: 1972
Make: Chevy
Model: Pickup

Would Acetone make a good flushing agent? I have plenty on hand as well as compressed air. I need to flush out the old mineral oil from the factory evaporator. I have removed the POA and the TXV so I just need to clean it out. I also have Asahiklin AK-225Asahiklin AK-225 in bulk quantities that we use for cleaning and degreasing sensitive electronic components. I also have a grip of Isopropanol.

Which of these would you use?


HECAT on Tue January 15, 2008 1:25 PM User is offline

You need to evaluate the Chemical compatibility with HNBR (seals), Nylon (barrier hoses), and Aluminum (components).

Acetone eats HNBR.

The AK-225 is a HCFC; using this for A/C flushing and releasing could be illegal.

Isopropanol; stay away from alcohol based products for A/C flushing.


HECAT: You support the Forum when you consider for your a/c parts.


bohica2xo on Tue January 15, 2008 1:43 PM User is offline

Acetone & compressed air is a bad plan in this application, and most others too.

Since this is a metal part, the elastomer issue is not a problem. The AK-225 is recomended for a final flush, but is too mild for some applications.

I would use a flush of mineral spirits or stoddard solvent first. I would fill the evaporator with the solvent, close it & let it stand for a while - overnight is good. Drain the solvent from the evaporator.

Plumb a length of hose from the evaporator to a suitable "catch can" - a 5 gallon bucket with a lid is good. Blow the remaining solvent out with plenty of air - make up a fitting that will allow full air flow. I use a coupling that matches my air hose, a length of rubber hose & a couple of clamps. The idea is to get 20 to 30 cfm of flow through the evaporator. A rubber tip blow gun is a waste of time - it makes plenty of noise, but does not build high velocities inside the evaporator. Better to use short blasts of high flow, and this works well even with a small compressor - just dump the tank a couple of times.

Once you have blasted the air through the evaporator, follow up with the AK-225. Use a few ounces, and blow it through the same way. Be sure to dispose of the AK-225 in a proper manner.


"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

tony1963 on Wed January 16, 2008 9:59 PM User is offline

I took a lot of heat recently by using isopropyl alcohol 70% as a flush agent, even though I have done this for several years with no issues. I chose the product on the recommendation of another shop due to this being an environmentally friendly product along with providing good results.

Since the product does contain 30% water, we use a good long blast of shop air afterwards followed by a flash period (to evaporate whatever is left). Then, shop air again.

Before adding any refrigerant or oil, a long vacuum is pulled.

Because of all of the ruckus here, I've switched over to isopropyl alcohol 91%. The 91% is stronger and contains less water. However, I caution you, this product is flammable and you must exercise extreme caution when flushing.

You are never going to get a system clinically clean because there is simply too much foreign material in the environment. A good flush with isopropyl alcohol will get the system clean. You can't simply jamb it together in the next 15 minutes. You'll have to force shop air through to remove any remaining moisture.

Grove Automotive Group, Inc.

An Alabama Corporation

HECAT on Thu January 17, 2008 10:00 AM User is offline


You have got to use something you know, trust, and works for you; and there is a huge amount of differing products available, that each one of us has had individual success and failures with. Some of the analysis given here is chemistry related, but mostly its our opinions and success stories.

IMHO, your success comes from your diligence and understanding of the need to remove the flushing agent. The ruckus about water is because we all know its not good for water to be in the system. The ruckus about alcohol is related to its affinity to corrode aluminum and form acids. These opinions/facts are based upon what problems these products could create if left in the system. Again I say; you mitigate, if not completely eliminate these issues with your diligence to remove.

B. is absolutely correct in his analysis that elastomer compatibly issues are irrelevant as this is a metal part we are cleaning.

My comments and chemical recommendations regarding compatibility are based upon the fact that the same type of elastomers are used in the flushing equipment we manufacture; and the fact that sometimes the system hoses are needed to access and flush a component. I believe that the introduction method (i.e. flushing equipment) is as critical for success as the chemical chosen. Cleaning these heat exchangers, as with many other cleaning and degreasing processes; will usually require some energy component to enhance the chemicals ability to scrub out the waste oils, sludge, and loosen debris (think: shaking the crap out of it, a parts washer brush, pulsing, vibration, ultrasonics, etc.). The chemical must also be introduced with the adequate velocity to carry away any weighted debris.

The key goal to any heat exchanger flushing method or chemical is to do no harm to the system and have a positive effect on removing undesirables. If we damage the components or add undesirables to the system; we have gone backwards from this goal.


HECAT: You support the Forum when you consider for your a/c parts.


Edited: Thu January 17, 2008 at 10:02 AM by HECAT

NickD on Thu January 17, 2008 12:36 PM User is offline

Ha, are you guys AC techs or janitors? Original post was on acetone, one chemical I have a great deal of respect for, burns the hell out of your mucous membranes in your respiratory system and can cause central nervous system damage.

In industry today, you won't even fine a can of Choke and carb cleaner, OHSA would fine you out of business, it's all soap and water, so drying is critical. My last go around was my AT cooler, was all copper and brass so used hydrochloric acid, rigged it to my garden hose with a good flush, blew it out a little and stuck it in my over at 220 for about 30 minutes. Wife ask me what I was baking, smells good, ha, said you don't want to eat this. Must have been an odor from last nights pizza.

Cleaning stuff in the vehicle is really a PITA, seems to be my favorite word today, can ruin your paint, plastic, and electronic parts, not to mention your eyes and lungs, using an air hose to blast that stuff out is putting a mist everywhere.

Ha, isn't the insides of an AC system suppose to be clean and stay that way? One reason for cleaning is somebody came out with the weird idea of changing refrigerant and the kind of oil you have to use, should find out who that guy is and kick him in the butt. A lot of these in particular toxic chemicals are putting a lot of crap into the air, even much more so than that old fashion refrigerant. Wonder if they considered that?

tony1963 on Thu January 17, 2008 9:25 PM User is offline

I doubt if there was much consideration to the shop that had to do the retrofit. I remember when R12 went away in the early 90's for the DIY and there were so many stories about retrofit that it scared the average person. I remember being told that you had to replace all of the soft lines because the new refrigerant would bleed through the lines in a very short time.

As time went on, most people figured out that retrofitting would produce cold air when they had hot air before. So, the number of trials went up until the process was better understood. Today, most retrofits give good results, even here in hot Alabama weather.

I try to use enviornmentally friendly products because disposal is a problem.

I just did a retrofit today on a 92 Explorer that will be sold in the car sales side. I pulled out the old steel drier (which was rusted and leaking somewhat), pulled the orifice tube, flushed the condenser (old continuous tube design) and then forced it clear with a long, long blast of shop air.

Add the proper amount of oil and new parts, it's blowing nice and cold.

Grove Automotive Group, Inc.

An Alabama Corporation

HECAT on Fri January 18, 2008 9:05 AM User is offline

I agree that retrofits may have created many flushing and cleaning issues, problems, phobias, and horror stories, which may have opened the door for a ton of "snake oil" junk to sold as the "magic in a can" solution. But retrofits did not start the need for cleaning the system.

The need for effective methods to remove debris from reusable components after a compressor failure, and the need to change out the oil for fresh, instead of total system replacement; existed well before retrofits came into play. HECAT started producing flushing equipment in 1982 after years of seeing the need by the founder and his associates (GM Training Engineers).


HECAT: You support the Forum when you consider for your a/c parts.


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