AC additive to seal up system??? Any ideas?

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Chris B.

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I was told that you should never use that stuff that seals up your AC system with a slow leak. That it gums up and ruins the system. Well today I was talking to a master ASE tech in a diesel repair shop and he told me the newer products for sealing up AC systems works really well and do not damage or gum up anything.
What do you guys think? I have a 1997 GMC Sierra with a slow AC leak I think. I was not blowing any cold air so I took it to my mecahnic who did a full service on it and pressure checked it and it held pressure with no signs of a leak. Now 8 months later I noticed the AC is not getting very cold again so I'm thinking the R134 is slowly leaking out. Any ideas??? Truck only has 78,000 miles.
 
8 months is a pretty slow leak, but unless you've got a lot of wet rainy weather it still fast enough that dye should be visible if your mechanic put some in there. If he didn't have hime dye it up and check it as soon as the AC gets nitocably weaker. If it leaks down and there's no dye visible anywhere, fill it up and let it sit overnight. Come morning, shove a sniffer in the vent and start the AC up.
 
I'd avoid a sealer, its a poor mans fix and can cause more harm than good. Use dye and/or a sniffer find the leak/leaks and fit it the right way.

Also keep in mind AC will not blow cold when it is cold out, AC needs hot weather to work properly. IMO it is also best to recharge an AC system during hot weather. If you opened up the system, starting from scratch and weighing the charge then it doesn't matter much. Opinions vary on this topic.
 
Most AC additives that I've seen are designed to repair deteriorating o-rings and the joint connections of the AC system itself. It's really a used car salesman's best friend and not a permanent fix.

I would bite the bullet and use dye to find the source of the leak. You may need a simple replacement of all its o-rings or, at worst, a new replacement component. It's always best to repair the system and keep out moisture/dirt than it is to ignore the problem or try to make a temporary fix it.
 
Check the fill ports. I've had my mother-in-laws truck spring a slow leak and turned out, the schreder (sp???) valve for the high pressure side had a slow leak. Easy 8 dollar fix.
 
If you put it in a clean system that still has pressure and it's not contaminated, it works.

If you wait till the system is empty and contaminated, big problem!

Another problem is when you put it in and then go to a pro who evacuates the system (per the laws), it can destroy their equipment when mixed with contaminated freon.

What ever you do, proceed with caution.

I did one with a trepidation in my home heat pump 2 years ago. It saved me from $5000 repair. YMMV.
 
Originally Posted By: friendly_jacek
Another problem is when you put it in and then go to a pro who evacuates the system (per the laws), it can destroy their equipment when mixed with contaminated freon.

x2. If I get a car in that has stop leak in it I wont recover the refrigerant thats still in it. The stop leak plugs up the soloniods in my machine and after the 2nd $1500 repair we said no more.

The stop leak works off of moisture. It will stay liquid in the AC system untill it blows a hose or somebody opens the system then it hardens into cement.

Destroys the entire system!
 
Sheesh, a 12 oz can of R134a is $9.97 at Walmart. Simply add refrigerant as needed and it should be good for another season if the leak remains small.

The truck may have only 78,000mi but its 15 years old, some parts deteriorate regardless of mileage.
 
There is one out there my indy recommends. Seal-tight? Seal-right? Comes with a short hose and a warning sticker.

My vintage of Volvo is well known for evap leaks. Huge & expensive problem. Made worse by the fact that to get the evap out, all the dash and front trim has to be removed. Huge pita.

Since I have a slow leak, I learned to recharge it on my own as cans of 134a are far cheaper than a replacement ($1600). So far the leak hasn't gotten worse. Till then, I'll keep feeding it.
 
Thanks guys! I'll skip the sealer and try the dye and recharge the slow leak. If I buy a recharge can at Wal-Mart how do I know how much to add in? How do I fill it exactly? Any special tools?
 
Originally Posted By: Chris B.
Thanks guys! I'll skip the sealer and try the dye and recharge the slow leak. If I buy a recharge can at Wal-Mart how do I know how much to add in? How do I fill it exactly? Any special tools?
If you do not have a high side guage your only guessing since you don't know how much is still in the system. The proper way is to recover whats in it, vacuum it and charge with a scale or charging station.
 
Originally Posted By: Chris B.
Thanks guys! I'll skip the sealer and try the dye and recharge the slow leak. If I buy a recharge can at Wal-Mart how do I know how much to add in? How do I fill it exactly? Any special tools?

You need a 134a can tap kit, looks like this:
http://www.amazon.com/Valve-Hose-Kit-R-134a-Systems/dp/B0007ZDRAI

You can get pretty close with one of these kits and a vent temp thermometer if you go slow, adding just enough to get the vent temps chilly again, preferably do it on a warm day and follow all directions.

I'd add one 12oz can for starters, monitor the vent temps as you go, A/C should be on Max setting. Better to be a little undercharged than overcharged.
 
Finally got around to working on my AC. Every single recharge kit at Wal-Mart and NAPA has some type of sealer in it. I looked at over 10 different brands and all of then have a sealer in it. I bought a brand called Artic something. I'm going to install it soon and report back.
 
Originally Posted By: Chris B.
Finally got around to working on my AC. Every single recharge kit at Wal-Mart and NAPA has some type of sealer in it. I looked at over 10 different brands and all of then have a sealer in it. I bought a brand called Artic something. I'm going to install it soon and report back.

If you're looking at the cans with a recharge hose attached to it, then yes all the ones I've seen have some kind of additives and/or sealer in them. You can buy cans of plain refrigerant, but it won't have a recharge hose attached. You'll need a manifold gauge set to recharge the system.
 
Originally Posted By: Chris B.
My leak is very slow. A full charge is pretty low at 8 months after the recharge.

Personally, I wouldn't put any goop in there. Having to add a can or two of straight 134a every 8 months is no big deal.
 
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