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thread sealant on AC pipe connections

11K views 22 replies 7 participants last post by  paulo57509 
#1 ·
Does anyone advise using a thread sealant on AC pipe joints? I mean on the joints between the condenser and the pipes going to the evaporator and the compressor. Also, on the joint between the accumulator and evaporator and the accumulator and the hose going to the suction end of the compressor?

If so, what type...Loctite? After Loctite thread sealant is the joint easy to undo?
 
#4 ·
the best stuff you can get is called nylog blue . Its a non hardening viscoelastic liquid made from refrigeration oil and used with any hfc refrigerant. you can take 1 tiny drop and stretch it out to a 2 feet string. I use it on every flair fitting and o-ring on commercial units, residential units and even auto hvac. It works great when resealing compressors, and I have never had a leak when using it. Any Hvac supply house will have it and it cost under $7. Here is the link to the manufacturers site http://www.refrigtech.com/Product/Sealants/Nylog/nylog_blue.html

here is a you tube video of it

Tim
 

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#5 ·
timothy47130 said:
the best stuff you can get is called nylog blue .Tim
Thanks for the tip, Tim, I'll check it out.

You claim to use it on O-rings as well??? I have a rubber rejuvenator I use on rubber idler wheel and pinch rollers that have hardened due to age but I am wondering if this stuff actually rejuvenates O-rings, or makes up for wear on them. Or are you talking new O-rings?

How would you apply it to an O-ring?
 
#7 ·
You can use snot if you wish (the stuff mentioned above - my HVAC-R husband calls it snot), but it isn't required for a compression fitting and might actually cause it to leak because it can't fully seat.
 
#8 ·
You just smear it on the o-ring new or used. And I have always used it on flare fittings and never had a leak. It just takes 1 tiny drop on the sealing surface of the flare.
 
#9 ·
Leeann_93 said:
You can use snot if you wish (the stuff mentioned above - my HVAC-R husband calls it snot), but it isn't required for a compression fitting and might actually cause it to leak because it can't fully seat.
I hear you Leann and I acknowledge your husband's expertise. My concern when googling compression fittings is the number of articles on compression fittings that leak. People are asking advice on how to stop the leaks, anywhere from water leaks to gas leaks.

I lived in an old house a while back where the natural gas pipes were connected with compression fittings. There was always a faint swamp-like gas odor although the house was so old it was hard to tell if it came from the old place or the gas pipes. A buddy who was visiting was a boilermaker and he insisted that I call the gas company, even though it was 1 in the morning.

I did and they did not hesitate about coming out. Several of the fittings were blowing bubbles when he swabbed them with a soap solution. He immediately shut the gas off and redid all the fittings, which were fortunately exposed in an unfinished basement. It was 4 in the morning before he finished and fortunately it's a free service here in Canada from the gas company.

On the 2001 Safari, the union is between brass and a softer material. Not sure if it's aluminum. Threads are designed to stretch as they are tightened and unfortunately they don't stretch across all threads evenly. I wonder about thread stretch between a harder and a softer material and whether the softer material gets damaged when the harder material tightens on it.

I would like to seal the outer threads at least, keeping the sealant away from the union itself.

I came across another product while researching Tim's Nylog suggestion. It's called Real-Tuff and it's a liquid Teflon. I don't see what harm it would do to start the compression fitting onto the threads then coat the final threads with something like liquid teflon.

I don't even know if 'snot' is available in Canada.
 
#10 ·
timothy47130 said:
You just smear it on the o-ring new or used. And I have always used it on flare fittings and never had a leak. It just takes 1 tiny drop on the sealing surface of the flare.
So far, I have not been able to locate it in Canada, but the refrigeration companies are closed for the weekend. Home Depot stocks Real-Tuff, a liquid teflon. Heard of that before?
 
#12 ·
sfeaver said:
The refrigeration places will have it. I got some at Masters in Hamilton, ON. Nylog is great stuff...
I guess Masters never ventured west. All their locations are across several mountain ranges, the wide prairie, and even some Great Lakes from me. :D

I'll check some dealers in Vancouver. Thanks for tip sfeaver.

What happens if a blob of Nylog gets sucked into the refrigerant? I notice there are two types, depending on the type of refrigerant. They claim it's an oil, does it mix with the refrigerant, like PAG oil?
 
#13 ·
I would think it would just mix with the oil since is made of refrigerant oil. And the Teflon sealant might work. Compressor seals are made of Teflon so it has to be refrigerant friendly.
 
#14 ·
timothy47130 said:
I would think it would just mix with the oil since is made of refrigerant oil. And the Teflon sealant might work. Compressor seals are made of Teflon so it has to be refrigerant friendly.
I was not planning to get the teflon anywhere near the seal, just around the outside threads. I think as Leann and CC claim, the compression fitting should do the job on its own. I'm just tired of losing refrigerant in old fittings.

I lose it so slowly that any leaks are very small. I already found one tiny leak where the condenser inlet pipe welds to the body. I sealed it with a large area application of JB Weld after spending considerable time cleaning the weld, the pipe, and the body where the JB weld is applied. I also cleaned any grease out of there with brake cleaner.
 
#15 ·
Lol I said it wrong. I meant most compressors use Teflon sealing rings inside them on the pistons. There for Teflon has to be refrigerant resistant.
 
#16 ·
timothy47130 said:
Lol I said it wrong. I meant most compressors use Teflon sealing rings inside them on the pistons. There for Teflon has to be refrigerant resistant.
The Canadian saga continues. Went to Home Depot for some Real-Tuff and the lady looked it up on the computer. Did not have it. I asked her to look it up on Google with Home Depot and Real-Tuff. It came up under Home Depot in US branches but not available in Canada.

Did you ever see that TV commercial where they are advertising a tea that is only available in Canada? There is an aristocratic Englishman sipping a cup and he says, "Only available in Canada? Pity". My new whine is, "Not available in Canada, eh? Pity". Followed by a few choice expletives that one can only acquire working in construction and industrial environments.

There was nothing like nylog but she did find me a small can of Masters Pro Dope with PTFE. PTFE is another name for Teflon. It's listed as a sealant for gasoline, natural gas, propane, oils, air, water, refrigerants, steam and CO2. For propane and butane it's listed at 2500 PSI maximum pressure.

It wont harden and they claim it is easy to remove the fitting.
 
#17 ·
I really don't understand the quest. If the pipes dont seal like they should from the factory nothing is going to keep the refrigerant from slowly leaking out. The a/c system doesnt come apart as much as say..the brake lines. If it has come apart multiple times for leaks and whatnot...well you need to just replace the unit or repipe and reflare. This is not a commercial unit that gets continuous service. I understand overkill, but the quest for sealant in this case seems counterproductive.
 
#18 ·
97cargocrawler said:
I really don't understand the quest. If the pipes dont seal like they should from the factory nothing is going to keep the refrigerant from slowly leaking out. The a/c system doesnt come apart as much as say..the brake lines. If it has come apart multiple times for leaks and whatnot...well you need to just replace the unit or repipe and reflare. This is not a commercial unit that gets continuous service. I understand overkill, but the quest for sealant in this case seems counterproductive.
Your right it is a little above and beyond and prob a little overkill. I use it just as a little extra insurance against leaks and because I always have some on hand in my hvac bag. Where I'm located it's no major quest to find it. I think it's at the point with gordo999 it's gotten personal. He's fighting a personal war with the Canadian government and is gonna do what ever it takes to find some. :D
 
#20 ·
97cargocrawler said:
I understand overkill, but the quest for sealant in this case seems counterproductive.
Hear you loud and clear CC. Unfortunately I have spent more on the AC recently than what makes sense and springing for $500 hundred more to renew the entire system is becoming counterproductive for me.

Most unfortunately, when I began the repairs by just changing the compressor, I did so in abject ignorance. The clutch was shot and I was thinking along the lines of changing a water pump or alternator. I learned the hard way.

Right now, I am trying to get a functional AC system so I can take a trip in a month or so. Ideally, I should have changed the condenser, evaporator, and the one-piece tubing from the condenser via the compressor to the accumulator. When I had them all out, however, they looked in surprisingly decent shape.

I know I am taking a chance but my biggest fear is having a collision the insurers deem a write off. I'll lose my shirt if I invest several thousand trying to bring the van into near-new condition. I'm retired (not retarded...although some may disagree) on a fixed income. I can't afford to throw money around as I once did, when I was younger and stupider.
 
#23 ·
I used that Nylog Blue stuff on the o-rings when I retrofitted my '92 Lumina to R134a. It came highly recommended by the members of an AC repair forum.

After pulling a vacuum for a few hours and letting the system sit overnight to make sure the empty and clean system was leak free, I partially filled the system and ran the sniffer over the connections. The detector signaled numerous leaks even though the system held vacuum for over 24 hours (static).

After scratching my head for a few minutes, I put the sniffer over the opened bottle of Nylog. You can guess the rest.
 
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