What's this AC component?

[Just_Randy]

Ok I looked at the MSDS for 4 different AC flushes. 3 are heptane and propanol. The 4th added toluene.

https://www.rockauto.com/genImages/1063/UAC_FlashFlush_22762.pdf

https://www.rockauto.com/genImages/577/8011256.pdf

https://www.rockauto.com/genImages/52/69991_sds_en.pdf (<--- isomers of heptane)
https://www.rockauto.com/genImages/1054/6545-6.pdf (<--- toluene)

Heptane and toluene are nonpolar solvents good for dissolving oil.
Propanol is a polar solvent that would dissolve polar molecules like salt.

I wouldn't expect to find many polar molecules (other than water) in an AC system but who really knows. Propanol could be a filler like acetone is in brake cleaner, or it could have a legit function like removing water. But I think the main solvent is heptane which I think is used because it is safer than toluene.

How to choose the right solvent for cleaning scientific instrumentation | Anton Paar Wiki

wiki.anton-paar.com

Anyway, I can't find a reason not to use brake cleaner to clear out the evaporator, particularly one that is high in toluene rather than filler and propellant. The best one I've found is Walmart's Super Tech brand.

So I guess I can hose out the evaporator with brake cleaner followed by 30 minutes of compressed air.

Thoughts?

 

[Shran]

Do it to it. There are a couple kinds of brake cleaner though - think red and green Brakleen - red is mostly tetrachloroethylene (excellent for heavy oils & grease) and green is acetone/methanol/toluene & heptane that works better on light oils, sticky stuff, paint, marker, etc. I'd probably use green for AC components.

30 minutes of compressed air is excessive, drain the excess liquid out and give it maybe a 30 second blast of air. Your vacuum pump will remove any remaining liquid or water.

Compressed air is often pretty humid, running a compressor for 30 minutes will compound that problem and you'll just end up introducing water vapor into the condenser if you run air through it that long.

 

[Just_Randy]

Do it to it. There are a couple kinds of brake cleaner though - think red and green Brakleen - red is mostly tetrachloroethylene (excellent for heavy oils & grease) and green is acetone/methanol/toluene & heptane that works better on light oils, sticky stuff, paint, marker, etc. I'd probably use green for AC components.

I usually avoid the CRC stuff. I always use Super Tech but during the covid lunacy I was forced to find another brand of brake cleaner which led me to this product and somewhat of an education:

https://www.amazon.com/ask/questions/asin/B085F3CWGY/2/ref=ask_ql_psf_ql_hza

How does this compare to the Wearever brand brake cleaner?

Answer:Thanks for the question. We have not tested the Wearever brand against our product. We can however compare the SDSs (http://docs.crcindustries.com/MSDS/93090.pdf )Wearever's has two types of heptane (methylhexane and n-heptane), it has methylcyclohexane and cyclohexane that are relatively mild solvents, naptha, and isopropyl alcohol to remove traces of humidity. It uses 3-5% of propellant. Ours (https://9777bfe7-e56c-4443-a8d8-a7a60b8941e3.filesusr.com/ugd/feb341_59c37f595bc64f78a5a162105db969fb.pdf) contains acetone, heptane, toluene and methanol. The toluene is a strong cleaner that does the bulk of the cleaning, acetone and methanol clean and displace humidity. We use the same propellant though we add a bit more so the product should maintain pressure better. In short, while CRC does great products we don't see anything in their formula that can justify a 2:1 price difference.

From that I concluded the product with the most toluene is what I wanted. And that turned out to be Super Tech. I bought a case of SQ and it was ok, but wouldn't buy again unless I couldn't find Super Tech. SQ won't dissolve grease or ignite quite as fast as Super Tech which is important to me because I use it as a flame thrower for killing wasps, fleas, and whatever. Roasting the place where animals bed down is better than insecticides that may not work or may harm the animals. We may see insecticide resistant bugs but I doubt we'll ever see flame resistant bugs

https://docs.crcindustries.com/MSDS/93090.pdf

http://linux.geodatapub.com/shipwebpages/sds%20sheets/fuel-oil-lube-degreasers/msds%20super%20tech%20brake%20cleaner.pdf

30 minutes of compressed air is excessive, drain the excess liquid out and give it maybe a 30 second blast of air. Your vacuum pump will remove any remaining liquid or water.

Compressed air is often pretty humid, running a compressor for 30 minutes will compound that problem and you'll just end up introducing water vapor into the condenser if you run air through it that long.

I thought 30 minutes was excessive too but that's what the flush video said to do on rockauto. I have a water separator on my compressor for painting that I used a long time ago to try to keep air lines from freezing while running nail guns in the cold, but it didn't work.

Video should be cued up:

 

[Shran]

Full disclosure, I don't use CRC products either. I feel they are way overpriced. All my brake cleaner & carb cleaner comes from Menards (FVP brand) and they carry both types. Their "non flammable" AKA CRC Red is great for gear lube & grease, I use a lot more of the "non chlorinated" type for general purposes and cleaning paint guns especially.

Main reason on the Menards stuff is because they often have a lot on hand, it's $2-3/can if you catch a sale and 11% off the rest of the time...buy a bunch and get a few free cans.

 

[Just_Randy]

We don't have Menards around here but I used to buy Super Tech for the same reason you buy the FVP: it's cheap and plentiful. Now that I know it's also the best I keep a large stock of it and stopped caring about the price. Usually when I find something good they stop making it lol

I have a friend up north who shops at Menards. I'll ask him to get a can of FVP and compare it. It would be good to have a second option.

 

[Just_Randy]

I put a couple cans of stop leak and another can of 134a and got it blowing cold then it leaked down within a couple hours. So I dribbled some oil in the schrader valve on the high side and found the leak. Pretty much what I figured.

 

[Just_Randy]

So I screwed in a fine thread sae bolt with some pipe sealer and that seems to have stopped it. On the low side I'll try a bolt with teflon tape and see if I can get through the rest of the summer.