R134a and Stop Leak - Good/Bad?

rharman · Apr 8, 2017

My wife's 1998 Lexus GS300 likely needs a top-off of refrigerant. Almost everything I see is InterDynamics and they all appear to have stop leak additives. I was hoping to just find a refrigerant/oil combo.

I've heard pro's and con's about the stop leak. Lexus says it may clog some internal orifices and possibly cause other damage.

Any thoughts or suggestions? I'd like to try charging it before taking to the dealer to look at.

Thanks.

WVBrady · Apr 9, 2017

If the system has stop leak in it, a/c places won't work on it, because it damages their recovery machinery and they cannot just vent the refrigerant to the atmosphere.

LS6 Tommy · Apr 9, 2017

Stop Leak gets filed in the same trash can as radiator stop leak and all the other Snake Oil products... Don't use it. Fix leaks, don't plug them...

Tommy

jayoldschool · Apr 9, 2017

Bad, so very bad. Never ever.

Fix leak, fill up on pure r134.

yeldogt · Apr 9, 2017

Is this the first time? Is it totally empty? Are you guessing?

A pro can find a major leak -- fix it and you are good to go for a couple hundred bucks.

Stop leak is the last ditch effort vs no AC at all. Normally, for an old car with a leaking evaporator thats never going to be fixed.

BillK · Apr 9, 2017

I just bought some R134 at Advance Auto Parts without any die or sealant. I think Wal Mart has it too

Doc · Apr 9, 2017

I buy 12oz cans of 134A supertech at walmart for $4.88 a can. cheapest around....

rharman · Apr 9, 2017

Yeah, I am not a fan of stop-leak products - snake oil seems an apt description.

First time any issue with this car's A/C in 19 years. It gets driven very little as evidenced by the 69,000 miles on it.

I just wasn't sure about adding only "pure" R134a and wondering if oil should be added too. I either see "pure" refrigerant or refrigerant + oil + stop-leak.

I figured I'd try adding freon and see how it goes but I wanted something with a gauge so I don't overfill. If it has a serious leak, I'll deal with that the correct way.

eddieK · Apr 10, 2017

rharman said:
My wife's 1998 Lexus GS300 likely needs a top-off of refrigerant. Almost everything I see is InterDynamics and they all appear to have stop leak additives. I was hoping to just find a refrigerant/oil combo.

I've heard pro's and con's about the stop leak. Lexus says it may clog some internal orifices and possibly cause other damage.

Any thoughts or suggestions? I'd like to try charging it before taking to the dealer to look at.

Thanks.

134a already has clogging issues (mainly at cap tubes and expansion valves) without leak sealants. Pull the charge, test the system to 400 PSI nitrogen and find the leaks. Weigh in the right charge.

75gmck25 · Apr 10, 2017

My understanding of how R134 stop leak works is that it causes the rubber o-rings and seals to expand, which may stop some leaks. However, it is not like stop leak for radiators (which fills holes) and I don't think it will fix leaks in metal parts (lines, compressor body), so it has limited uses.

As others have already mentioned an R134 system also has some very small orifice areas and/or expansion valves, and other parts that are used to keep the high/low sides working together to provide cooling. You do not want to add any foreign materials that might plug anything or even reduce its size.

Brcue

mpire · Apr 10, 2017

Stop leak absolutely stops the system from leaking.

It also burns up your compressor. So...

If you have a problem that stop leak can fix, you have a pretty easy problem. Find the leak, replace the non moving bad parts yourself with the cheapest thing you can find because its all the same. Then recharge with gauges and vacuum pump from harbor freight. They will only work about 5 times before they break, but whatever.

Honestly, its cheaper to replace every non-moving part of your AC system in your car than it is to take it to an AC shop.

That stuff is VOODOO and the pricing has no relation to the actual work.

That being said, you gotta get your hands dirty to save money so that's the decision you gotta make.

I got BMWs, and I can replace everything but the compressor with new parts for under $600. (The evaporator had a leak, lots of oil and grime by obvious leak, $130, plus dryer, $30, plus O-rings, $12.)

I replaced most of my Ford Ranger AC system including a new compressor for a lot less than that. (Compressor $120, O-rings $9, Dryer, $18, expansion valve $15)

If the system is empty, always replace the fill/test valves, the dryer, and all the O-rings you can get to easily.

Both are blowing ice cold. Filled with refrigerant by weight according to the manufacturers specifications.

stolidedog · Jul 21, 2017

I recently replaced the compressor, condensor, accumulator, suction and liquid lines in my 2001 mustang. I also completely flushed the evap. The hoses have the expansion valve and orifice tube built in.

I stupidly used the A/C pro freon which has stop leak. I'm concerned. Should I have the system evac'd and replaced with pure freon or do I need to start all over again? I haven't run the A/C much. Maybe an hour or two total, but I filled it two weeks ago.

TangoFoxTrot · Jul 21, 2017

You can get the pure r134 at places like Home Depot and Walmart.

I personally would just top off a 20 year old car like that and drive it, but the right way would vacuum it out, fill with nitrogen, find the leak, vacuum down, weigh in correct charge, etc.

I had an old Lexus that had a tiny evaporator leak that was too expensive to fix. Put a $5 can of r134 every two years or so and it blew ice cubes.

JRC3 · Jul 21, 2017

I can't believe they sell stop leak. Auto A/c is brutal and no stop leak is gonna fix a leak in it.

Doc said:
I buy 12oz cans of 134A supertech at walmart for $4.88 a can. cheapest around....

$4.49 at Rural King. I remember buying R12 back in the later 80s for $0.88 a can.

stolidedog · Jul 21, 2017

TangoFoxTrot said:
You can get the pure r134 at places like Home Depot and Walmart.

I personally would just top off a 20 year old car like that and drive it, but the right way would vacuum it out, fill with nitrogen, find the leak, vacuum down, weigh in correct charge, etc.

I had an old Lexus that had a tiny evaporator leak that was too expensive to fix. Put a $5 can of r134 every two years or so and it blew ice cubes.

My problem wasn't a leak at all. I rebuilt the A/C (except evaporator) and vacuumed for 90 minutes and the pressure stayed at -28 PSI...all good.

The problem is I bought freon at AutoZone and the A/C pro can had the handy gauge, line and trigger pump and looked easy to fill. I didn't think about the fact it had stop leak in it.

My question is can / should I just evac and fill again with pure freon. Will that remove any dyes or stop leak the A/C pro freon put in?

I know it is an old car, but it is a second car and I've had too much other stuff replaced. I live in the Phoenix area and you cannot live without A/C in the summer. You can't sell a car that way either.

TangoFoxTrot · Jul 21, 2017

stolidedog said:
My problem wasn't a leak at all. I rebuilt the A/C (except evaporator) and vacuumed for 90 minutes and the pressure stayed at -28 PSI...all good.

The problem is I bought freon at AutoZone and the A/C pro can had the handy gauge, line and trigger pump and looked easy to fill. I didn't think about the fact it had stop leak in it.

My question is can / should I just evac and fill again with pure freon. Will that remove any dyes or stop leak the A/C pro freon put in?

I know it is an old car, but it is a second car and I've had too much other stuff replaced. I live in the Phoenix area and you cannot live without A/C in the summer. You can't sell a car that way either.

I was responding to the original post

JerryC · Jul 22, 2017

stolidedog said:
My problem wasn't a leak at all. I rebuilt the A/C (except evaporator) and vacuumed for 90 minutes and the pressure stayed at -28 PSI...all good.

The problem is I bought freon at AutoZone and the A/C pro can had the handy gauge, line and trigger pump and looked easy to fill. I didn't think about the fact it had stop leak in it.

My question is can / should I just evac and fill again with pure freon. Will that remove any dyes or stop leak the A/C pro freon put in?

I know it is an old car, but it is a second car and I've had too much other stuff replaced. I live in the Phoenix area and you cannot live without A/C in the summer. You can't sell a car that way either.

IMHO, I'd leave it in there, it has the stop leak that works on rubber parts, not the kind that turns into goo when it hits water or air. It shouldn't hurt anything.

6768rogues · Jul 22, 2017

The car is almost 20 years old. Most systems do not need to lose very much refrigerant to trip the low pressure switch and disable the system. Some will get a little low and be cool but not cold. I would buy a can and a hose and put some in to see if it works. I have had some that took about a half pound every three years or so and then worked great for another three years. One Chevy that I owned took less than a half pound every spring and then was freezing cold all summer. If you put some in and it leaks right back out, you can either put money in an old car, drive with the window down or unload it.

stolidedog · Jul 23, 2017

JerryC said:
IMHO, I'd leave it in there, it has the stop leak that works on rubber parts, not the kind that turns into goo when it hits water or air. It shouldn't hurt anything.

Thanks JerryC, that is helpful. The reason for my concern is it gets icy cold some days, luke warm others. Recall I'm in AZ where it is hot this time of year. Sometimes if goes cold, warm, cold while driving. I don't think it is a blend door problem. Also the compress doesn't seem to cycle on and off.

The stupid AC Pro gauge kept saying it was low and I kept adding. The next day I check again and it was super over charged. I released some until it was right (with a good set of manifold gauges this time).

I think I'll have a mechanic evac-pull the system and re-charge and see what happens.

PoorOwner · Jul 23, 2017

Don't always assume it's the evap. I have had to change out the high side hose around that age Lexus 2jz engine

wildbill23c · Jul 23, 2017

Avoid the stop leak ****, it don't stop leaks, it stops the whole system from working by plugging up all the internal passages which in new vehicles with R134A are extremely small...not as big of an issue with R12 systems, but still DO NOT use anything that has stop leak in it. You can look around and get cans for R134A refrigerant only, use it. You need to get a manifold gauge set and a vacuum pump and do this properly. Those little gauges on the off the shelf cans are junk and DO NOT give an accurate reading, they give you some sort of information on the low side of the system only, you need to see both sides when you recharge a system so you can monitor pressures accurately. You can get an oil injector to inject the oil into your AC system. Every system is different so you'll have to find out how much oil and refrigerant your system needs. I'd suggest if its not cooling to add some dye and charge the system, find and fix the leaks, vacuum the system down, and recharge it properly, otherwise you can damage the system by adding too much refrigerant and having such high pressures it causes leaks.

I bought my manifold gauge set and vacuum pump at Harbor Freight, new compressor, accumulator/drier, o-ring set, oil injector, dye injector, R134a, PAG oil, cost about $500 to get everything in the end but the AC in my 1988 Ford Bronco 2 is working great. I now have the proper tools to work on these systems in the future if needed, or if I get another vehicle in the future I'll already have the gauges and vacuum pump, oil injector, etc.

Many leaks are at junctions where O-rings exist, the connections to the compressor, etc. Don't assume your leak is the evaporator or the condenser. Also, on newer vehicles the condenser has to be replaced you can't flush them anymore due to the extremely small passages.

JerryC · Jul 23, 2017

stolidedog said:
Thanks JerryC, that is helpful. The reason for my concern is it gets icy cold some days, luke warm others. Recall I'm in AZ where it is hot this time of year. Sometimes if goes cold, warm, cold while driving. I don't think it is a blend door problem. Also the compress doesn't seem to cycle on and off.

The stupid AC Pro gauge kept saying it was low and I kept adding. The next day I check again and it was super over charged. I released some until it was right (with a good set of manifold gauges this time).

I think I'll have a mechanic evac-pull the system and re-charge and see what happens.

A better idea would be to just tell them what's going on see if they can diagnose the issue. If it is a blend door for example, you don't want to pay for a needless evac and recharge.

It could be a few things causing your problem, but I'd guess the cold-warm-cold is your comp kicking on and off and that could be either too much or too little refrigerant. Too little and the low pressure switch shuts it off, and too much the high pressure switch shuts it off. Also if your fan isn't working properly the pressure will climb and it will cool poorly and if it keeps climbing the HP cut off will kick in.

stolidedog · Aug 3, 2017

Well it acted up again. I tested it with a manifold gauge set. It was 95 degrees roughly this morning and the low side was ~40 PSI and the high side was 375 PSI. Too low on the low side and too high on the high side. Tells me there is a blockage. Probably in the orifice tube. I think I will evac and replace the liquid line (orifice tube is crimped in). I don't want to run it anymore are risk destroying the compressor.

Question: Is that enough or do I have to replace once again the condenser, suction line and accumulator and re-flush the evap or just an evac and line replacement enough?

Ruger_556 · Aug 3, 2017

eddieK said:
134a already has clogging issues (mainly at cap tubes and expansion valves) without leak sealants. Pull the charge, test the system to 400 PSI nitrogen and find the leaks. Weigh in the right charge.

400 psi? I guess if you want to make leaks to fix... 200 psi is plenty sufficient to find any leaks.

JerryC · Aug 4, 2017

stolidedog said:
Well it acted up again. I tested it with a manifold gauge set. It was 95 degrees roughly this morning and the low side was ~40 PSI and the high side was 375 PSI. Too low on the low side and too high on the high side. Tells me there is a blockage. Probably in the orifice tube. I think I will evac and replace the liquid line (orifice tube is crimped in). I don't want to run it anymore are risk destroying the compressor.

Question: Is that enough or do I have to replace once again the condenser, suction line and accumulator and re-flush the evap or just an evac and line replacement enough?

375 is really high, yikes!

Make sure you are getting enough airflow through the condenser. Fans working, shroud in place, are there ways the air can bypass the condenser? You have a new condenser, is the radiator dirty and restricting airflow?

If the compressor is good you don't have replace or flush the other parts. If the compressor is throwing metal shavings or other debris through the system then you need to replace and/or flush everything.

stolidedog · Aug 4, 2017

JerryC said:
375 is really high, yikes!

Make sure you are getting enough airflow through the condenser. Fans working, shroud in place, are there ways the air can bypass the condenser? You have a new condenser, is the radiator dirty and restricting airflow?

If the compressor is good you don't have replace or flush the other parts. If the compressor is throwing metal shavings or other debris through the system then you need to replace and/or flush everything.

Thanks for the response. Yeah the fan is working. In my car there isn't a fan shroud, just the electric fan behind the radiator. The compressor is new as well as everything else in the A/C system except the evap, which was thoroughly flushed. Maybe the radiator needs a clean, but the engine heat stays normal so I wouldn't think it is too bad to restrict so much air flow.

I bought all the parts at AutoZone. Everything should be under warranty. I'm going to talk to them. I'm going to try to replace the liquid line and see if it makes a difference. Maybe I got a bad one or maybe the Stop Leak in the freon made it clog up.

As an FYI, since I've rebuilt the system the car has probably run only a few hours, maybe 5 so hopefully there isn't any damage to the new parts...I hope!!!

JerryC · Aug 4, 2017

I've always been surprised how much stuff can be in a radiator and the engine stays cool, they are clearly overbuilt knowing they will load up with bugs and junk. I think the radiator being full of junk is a long shot, but it doesn't cost anything to clean it before you start spending money and a clean radiator won't hurt anything.

Can you tell if the fan is moving a lot of air? Does it feel like that from the front of the condenser?

stolidedog · Aug 4, 2017

JerryC said:
I've always been surprised how much stuff can be in a radiator and the engine stays cool, they are clearly overbuilt knowing they will load up with bugs and junk. I think the radiator being full of junk is a long shot, but it doesn't cost anything to clean it before you start spending money and a clean radiator won't hurt anything.

Can you tell if the fan is moving a lot of air? Does it feel like that from the front of the condenser?

Thanks again Jerry. I think it is worth a try to clean the radiator. Its an old car and I bought it a year ago and I'm betting nobody has cleaned it so I'll give that a try. What's the best way to do that? Should I just take it to a car wash and power wash it with water?

I've only felt the fan from the engine side and it feels like it blows pretty good. You are saying check it from the condenser side, so would the just mean put my hand against it and see if I feel a good suction?

JerryC · Aug 4, 2017

stolidedog said:
Thanks again Jerry. I think it is worth a try to clean the radiator. Its an old car and I bought it a year ago and I'm betting nobody has cleaned it so I'll give that a try. What's the best way to do that? Should I just take it to a car wash and power wash it with water?

I've only felt the fan from the engine side and it feels like it blows pretty good. You are saying check it from the condenser side, so would the just mean put my hand against it and see if I feel a good suction?

I wouldn't use a power washer, you might bend the fins unless you have it out of the car and get back bit so you don't hit full force. I use a garden hose with a sprayer and spray from the back side. If you can easily remove it to clean it you can do a much better job.

Yes, put your hand in front of the condenser and feel how much air you have going into it. That should give an idea of how restricted the airflow is, or of how much is bypassing the condenser by going through gaps between the condenser and the radiator.

stolidedog · Aug 4, 2017

JerryC said:
I wouldn't use a power washer, you might bend the fins unless you have it out of the car and get back bit so you don't hit full force. I use a garden hose with a sprayer and spray from the back side. If you can easily remove it to clean it you can do a much better job.

Yes, put your hand in front of the condenser and feel how much air you have going into it. That should give an idea of how restricted the airflow is, or of how much is bypassing the condenser by going through gaps between the condenser and the radiator.

Ok cool. I'll give it a shot and let you know. I'll yank the radiator and give it a good wash. I felt the air flow from front of the condenser and it seemed decent to me. I don't know what to compare it to but certainly air was flowing through.

It is roughly 85 degrees here now and the low side PSI was 35 and the high side was 325.

Milton Shaw · Aug 4, 2017

Car a/c condensers don't cool good with the car sitting still. They need the air flow of driving to get the max cooling and the pressures where you want them to be to test the system. Try either putting a big fan blowing in front of the car or just spray the condenser with a water hose and temps and pressures with drop like crazy....If you can pull the top radiator mount and separate them and look to see if the front is clogged before you go to all the trouble of draining antifreeze out.

stolidedog · Aug 5, 2017

stolidedog said:
Ok cool. I'll give it a shot and let you know. I'll yank the radiator and give it a good wash. I felt the air flow from front of the condenser and it seemed decent to me. I don't know what to compare it to but certainly air was flowing through.

It is roughly 85 degrees here now and the low side PSI was 35 and the high side was 325.

I couldn't resist. I pulled the liquid line and cut the tube and pulled out the orifice tube. It was clogged and metal shavings. The new (not rebuilt) compressor I bought from AutoZone must have been bad. Hopefully they will warranty all of it. I just hate doing all this work again.

steve308 · Aug 5, 2017

I'd put money that the New compressor was good and the metal came from the one you replaced originally. With the news of the shavings, Id recommend a complete systems flush not once, not twice but at least three times. Install a filter in the line to collect any shavings you missed. Most AC condensers cannot be successfully flushed of metal shavings, be prepared to change it. I've always treated the 134 AC systems as a scheduled service required system. Once it's 5 years old have a shop pull down the refrigerant, pull a vacuum, refill with the proper weight of refrigerant.

stolidedog · Aug 5, 2017

steve308 said:
I'd put money that the New compressor was good and the metal came from the one you replaced originally. With the news of the shavings, Id recommend a complete systems flush not once, not twice but at least three times. Install a filter in the line to collect any shavings you missed. Most AC condensers cannot be successfully flushed of metal shavings, be prepared to change it. I've always treated the 134 AC systems as a scheduled service required system. Once it's 5 years old have a shop pull down the refrigerant, pull a vacuum, refill with the proper weight of refrigerant.

Thanks Steve,

I did a complete rebuild of everything, except the evaporator. I flushed the heck out of it, three times. I was clean. Maybe your right and stuff remained but I don't trust anything now. I don't want to go through this hassle again. I'm going to see if AutoZone will replace all the parts. Sounds like they will. I will flush the evap again obviously.

77thor · Aug 5, 2017

LS6 Tommy said:
... Dont use it. Fix leaks, don't plug them...

Totally agree.

stolidedog · Aug 5, 2017

I sprayed 7 quarts of a/c flush through the evap. The first quart had quite a bit of sediment. The 3rd - 7th came our really clear but just a few tiny metal flakes keep showing up. I don't know what to do? Do I need to replace the evap? On a 2001 Mustang this requires removing the whole steering wheel and entire dash. Looks like a major PITA.

JerryC · Aug 5, 2017

Man, that's bad news. I too bought my comp from AutoZone, new not a reman. Did you make sure it had oil and spun it by hand several times before you installed it?

As for the evaporator, it sounds like it's easier to flush it several more times than to replace it. See if they make screen for the suction side of the compressor and install it with new compressor.

stolidedog · Aug 5, 2017

JerryC said:
Man, that's bad news. I too bought my comp from AutoZone, new not a reman. Did you make sure it had oil and spun it by hand several times before you installed it?

As for the evaporator, it sounds like it's easier to flush it several more times than to replace it. See if they make screen for the suction side of the compressor and install it with new compressor.

I bet the AutoZone compressor was fine. I think just more residual mess in the evap then I realized. I agree with you, I going to spend another $50 on another gallon of flush and see if it gets better. If I had to count the specks I see, I would say around a dozen. They are smaller than a grain of sand, but you can see the refection in the light.

Anyone know if buying the flush at the local auto parts store is the way to go? I heard mineral spirits, yes / no from different people on forums like this. Others say acetone, dunno.

LS6 Tommy · Aug 6, 2017

stolidedog said:
My problem wasn't a leak at all. I rebuilt the A/C (except evaporator) and vacuumed for 90 minutes and the pressure stayed at -28 PSI...all good.

stolidedog said:
Well it acted up again. I tested it with a manifold gauge set. It was 95 degrees roughly this morning and the low side was ~40 PSI and the high side was 375 PSI. Too low on the low side and too high on the high side. Tells me there is a blockage. Probably in the orifice tube. I think I will evac and replace the liquid line (orifice tube is crimped in). I don't want to run it anymore are risk destroying the compressor.

Question: Is that enough or do I have to replace once again the condenser, suction line and accumulator and re-flush the evap or just an evac and line replacement enough?

JerryC said:
375 is really high, yikes!

Make sure you are getting enough airflow through the condenser. Fans working, shroud in place, are there ways the air can bypass the condenser? You have a new condenser, is the radiator dirty and restricting airflow?

If the compressor is good you don't have replace or flush the other parts. If the compressor is throwing metal shavings or other debris through the system then you need to replace and/or flush everything.

First of all, I probably post this at least once a season- YOU CANNOT LEAK CHECK WITH A VACUUM. PERIOD.

Now that I got that off my chest my OCD won't flare up any worse. :lol_hitti

It definitely sounds like a restriction caused overcharge. Recover the refrigerant, Get your new liquid line and a new receiver/drier if it has one. Blow a can of flush through the system. replace the liquid line and receiver/drier. Leak check with dehydrated nitrogen, evacuate and weigh in your new refrigerant (without leak stop).

Tommy

stolidedog · Aug 6, 2017

LS6 Tommy said:
First of all, I probably post this at least once a season- YOU CANNOT LEAK CHECK WITH A VACUUM. PERIOD.

Now that I got that off my chest my OCD won't flare up any worse.

It definitely sounds like a restriction caused overcharge. Recover the refrigerant, Get your new liquid line and a new receiver/drier if it has one. Blow a can of flush through the system. replace the liquid line and receiver/drier. Leak check with dehydrated nitrogen, evacuate and weigh in your new refrigerant (without leak stop).

Tommy

Tommy thanks for your response but I don't understand your comment. My problem isn't a leaking system nor overcharge. It turns out the orifice tube got clogged after a rebuild. I'm thinking now that there is still residue in the evaporator even though I flushed it several times.

I probably should not be posting to this forum. I originally did thinking the freon I used had stop leak and that was causing the blockage. Turns out that isn't the case.

I've decided instead of spending more money on expensive and messy flush chemicals and using the 1QT canister sprayer attached to a compressor, I'm going to hire a mechanic who has a HECAT or similar system to flush it and get rid of any remaining contaminates once and for all. I can't keep wasting time and money on this.

Thanks again for responding.

R134a and Stop Leak - Good/Bad?

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