Automotive Air Conditioning Information Forum

(I did read the he-cat-in flushing document mentioned the sticky above. I did use a 1qt flush gun because it is all I had)

What's this stuff I'm flushing out of an evaporator?

Black chunks. If they are pressed they smear. My guess is solidified oil? Some have the shape of the outside of a tube.

The interesting thing is the round thing/glob. green on one side, black on the other. For scale, the round thing is about 1/4" diameter

This is from a 1980's VW Vanagon evaporator which has ben sitting for who knows how long (Will not be using this in my build)

This had ACPro Solvent cleaner in it for a week and then if was flushed several times and only on like the 4th flush this started coming out. The flush was re-used each time by straining through paper towel. Thought is to keep reusing the flush until bits no longer come out and then flush with non-used new flush.

To me, it looks like the residue left behind from burned oil, also known as "coke."

Air and moisture in an overworked and neglected system.

Mineral oil in an A/C system was pretty stable. Unless you add oxygen or water. Usually air raises the head pressure and the discharge temperature, which helps oxidize or "coke" the oil.

Moisture creeps in to systems via hose transpiration. There is even a standard for it from the hose manufacturers. That is why you replace dryers on systems that have remained closed.

John - did you even open a "black death" Ford system?

B

bohica2xo wrote: ↑Sat Sep 09, 2023 8:45 am John - did you even open a "black death" Ford system?

No, I never had the "pleasure"

still flushing this Evap. Like 30? quart flushes thorough. This is the result today after sitting for another week. When those black speck dry they are green.

I can see why the He-Cat process/machine uses pulses. this stuff doesn't come out with a constant flush. Only with rotating the quart canister to pulse some air.

The evap is 32 pass and about 4"x5"x26". It holds about 2 quarts of fluid. It is an OEM VW Vanagon Evap, I'm not using it in my project. Now I'm just curious how many times I'll need to flush it to get it clean.

Green color of residue suggests copper salts from corrosion of the copper tubes.

Cusser wrote: ↑Sat Sep 16, 2023 6:03 am Green color of residue suggests copper salts from corrosion of the copper tubes.

Hmm, you think I may be causing this by leaving this solvent based flush in there for days thinking I'm diluting the bad stuff?

I was wondering if the green is the residue of the dye that was in the system and now in the flush I'm re-re-re-reusing.