FFG High Temp A/C Flush, 1 Gallon (Flash Point Greater Than 250 F)

In a nutshell: Never having used oil-based flush before, I decided to try the Mastercool A/C Fast Flush, but to be on the thorough side, follow it up with a final solvent-based flush. After several passes with the Fast Flush, I was very disappointed to see how much particulates and gunk the solvent flush released (that the Fast Flush hadn’t removed). (I used Four Seasons 69994 Super Flush Solvent, which seems to be about the least expensive solvent-based flush.) The first photo shows fine aluminum particles (trapped in a filter) that the solvent-based flush DID get out, but the previous four flushes with Fast Flush DIDN’T. If I had it to do again, I wouldn’t use Fast Flush or any oil-based flush. In detail: There are basically two kinds of air conditioning flush: traditional solvent-based, and newer oil-based. All of the solvent-based flushes are highly volatile, typically flammable, not good for the environment, and not particularly good for your health. The oil-based flushes are generally far less volatile, not flammable, and generally not toxic. But the biggest difference between the two is that because the solvent flush is so volatile, it’s difficult to leave any behind in the components you are flushing. The oil based flush is just the opposite – very difficult to remove, as many have noted. I used about two quarts of Fast Flush to flush my evaporator and hoses. (I replaced the condenser, which had served as a rock shield for my radiator for 160K miles.) Initially, I was pretty happy with how much gunk the Fast Flush removed. But trying to flush the evaporator quickly showed a drawback – very difficult to remove. Using compressed air, I’d think I’d gotten it all out, but upon rotating the evap to a different orientation, more would get blown out. I did this four times, and every time, more flush came out. And don’t think of liquid in, liquid out. That’s what you have initially, but when you blow air through, you get big clouds of ultra-fine (but presumably non-toxic) mist out. This stuff does evaporate, but very, very slowly. The second picture shows some that spilled on my driveway a couple of days before the picture was taken. It’s definite not evaporating. This is pretty messy stuff to use. Initially, I envisioned that the final flush with the solvent flush would simply be removing the thin layer of Fast Flush oil that remained. As you can see from the particulates photo, there was more to it. I think a better way of thinking about the results of the Fast Flush was that there were small pools of liquid remaining – especially in the evaporator – and that those small pools contained particulates and gunk. The solvent-based flush dissolved the remaining Fast Flush, and carried it, the gunk, and particulates out of the system. The very limited Mastercool instructions on the can make it sound like a quick blast of shop air is all it takes to remove the flush. Don't believe it. And curiously, Mastercool doesn't even list this product on their website, but they do seem to feature their solvent-based product. Bottom line, for the price of a gallon of Fast Flush oil-based flush, I could have just about bought a brand new evaporator core. Buying a new evap, and using a quart of solvent-based flush for the hoses would probably have been a better idea.

Flush worked excellent!!!!!! Did 3 systems and all my car A/C's work great.

Great product. Flushed 2 cars with it - one was only evaporator and lines, the second one was everything except compressor and dryer. Works like a charm. Don't get sprayed in the face though like me, its not fun ;-)

Doesn’t evaporate like other cleaner, oil based fluid. Did notice the system get cleaner after flushing but you kinda have to run air thru the system to push all the fluid out.

I used it to flush the system in my 04 GMC SAVANA 4.8L and it was ok but I was hoping that it would evaporate quickly kind of like acetone or alcohol but it didn’t. I have no idea what it is but smells and feels more like mineral spirits of some kind. That’s why I blew a lot of compressed air after the flush to get rid of as much of it as possible and left the system open with cotton cloth zip tied to the openings for a couple of days to let it evaporate better. After that I blew the system again with air and put everything together, vacuumed it , recharged and it is working. Again I am not an expert and I don’t know how compatible the cleaner is with the ac components and oil that’s why I did what I did to make sure I am minimizing the risk of failure. It’s been only 3 months but so far I am happy.