18-days ago, 01-April, my A/C wasn't cooling at all; it had been years since it had ever needed any refrigerant added.

I added two 12-ounce cans r134a and began to get some cooling.

I don't know just how many days before it all lost out; but, yesterday, it would not cool at all; it may have all leaked out days ago.

I have found this U-V Dye in 4-ounce cans, three for $30; or,one 12-ounce can $30; it seems to me like it would be smarter to get the three 4-ounce cans.

My question is --- will a single 4-ounce can be enough to display the leak ?

I have never used the Dye before and have no idea and internet searching has not proved very helpful.

I do have the U-V Flashlight.

Also, will it hurt anything to just leave the stuff in there ?

If I have to pull a vacuum, would it be okay to add a can with the refrigerant so that any future leaks could be spotted from the get go, or does it work that way ?

Could a bad O-Ring at a line connection leak that rapidly ?

 

4 ounces would be enough. Once you put the dye in, it stays in unless you flush the system. No need to keep adding dye. It does not hurt anything, some GM cars come from the factory with the dye already inside the system.

Yes, just a o-ring will leak bad enough to empty the system. I had to replace a o-ring in my wife's honda just last week. I knew it had a bad leak, it wasn't low, it was empty. Instead of using refrigerant, I do the big no-no and use compressed shop air. That's how I found when her condensor had a hole in it, and just the other day i is how I found the o-ring on the condensor leaking. I pump the system up to 120psi and listen for leaks and use soapy water in a spray bottle.

If you do not want to contaminate your system with air, you can refill it with refrigerant and the dye, and you can use the flashlight AND you can also use soapy water in a spray bottle to find leaks. Places you might not check that are common for leaks are the test ports themselves.

Once you get this deep into it, you need to go to harbor freight and get a vacuum pump and a set of gauges. It will set you back a couple $100, but go get a quote from a shop that does A/C work and you find it is money well spent. I put my systems on a vacuum pump for several hours, to sometimes a day for the ones I put shop air into. Never had a problem so far.

 

If you had no cooling at all recently, there's a good chance all refrigerant had leaked out and moisture got in. You can top off a system that has some cooling, because that means there is at least some refrigerant in the system. I've done this many times on various vehicles, with about 80% success. If some refrigerant is present (evidenced by at least marginal cooling), there's enough pressure to keep moisture out. But once moisture gets in, you have to do a full evacuation and refill. Otherwise, the moisture freezes up and causes trouble even if the correct amount of refrigerant is present. If the system was empty, or nearly so (meaning moisture likely got in), adding refrigerant is a waste of time without doing a full vacuum evacuation first.

Like Dave said, it's very worthwhile and cost effective to learn how to do a full service yourself. It's not difficult and we can walk you through the process. You can use dye to find leaks, but I've never bothered. I've done the compressed air and soapy water test to find leaks. If using compressed air, you have to make sure to pull a vacuum for at least several hours to extract any moisture you may have introduced. Once again, not a big deal. Or if the system still has some refrigerant, it's already pressurized so you can go straight to the soapy water test.

You may also want to invest in a refrigerant sniffer to find leaks. It's a little handheld device that beeps in presence of refrigerant. They are cheap nowadays, under $50. Obviously you can't use it on an empty system, but it works well if there's some refrigerant in the system.

A refrigerant sniffer works well to check the evaporator for leaks. Since it's inside the ductwork, you can't visually check it without major disassembly. So even if you used dye, you'd never see the evidence of a leaking evaporator. To check with a sniffer, let the truck sit overnight with the windows open. The idea is leaking refrigerant will collect in the ductwork. Without opening the door (which will cause a rush of air and disperse any leaking refrigerant), lean through the passenger window. Stick the sniffer probe into the vent and see if you get any beeping. If so, the evaporator is leaking.

 

That shop air sounds a lot less hard on my bill-fold than adding and losing refrigerant and dye.

I already have a really good vacuum pump and a good set of gauges.

I guess I already know your answer; but, were you in my boots, would you just forego the expensive dye/refrigerant method and shoot her full of shop air ?

I have a big air-dryer/filter contraption that is meant to be wall-mounted but I have it fixed on a wooden carrier with handle and with male and female couplers such that I can connect it at the end of a long hose and connect whatever tool to that, so I have a better chance than most at preventing moisture.

 

Maybe a dumb question; but, how do you guys get the shop air in there; through the gauges or via some sort of adapter at the inlet fitting ?

 

I cobbled some fittings together to connect the gauge set to shop air.

Do you have a MIG or TIG welder? Even better than shop air, use welding shield gas. It's going to be relatively dry compared to compressed air, so there's less moisture to extract when done.

If you're planning to take the truck to an AC shop, you probably want to skip the compressed air leak check. The guys would probably lock up if you told them and then want to replace every component.

 

Thanks; I will see if I have something that will work.

Two things I learned a long time ago :

1. Keep my mouth shut about such things.

2. No matter what it is short of major surgery (on me), don't involve anyone else --- ever.

When I involve anyone else, it is seldom a good outcome, I don't care how many credentials they have.

Even if I have no idea what I am doing nor where to begin, my outcome is ALWAYS better when I just do it myself.

Now, that thing the wife drives, that is another thing entirely; her "guy", the only one anywhere around I would trust to do anything, pulled his doors closed for the last time 31-December and I don't know what she is going to do if it ever gives any more problems; just drive it until the wheels fall off and junk it I guess.

She has a perfectly good 1991.5 Dodge/Cummins that looks like a show truck with big plushy captain's chairs and many wonderful goodies and custom improvements far too numerous to mention; but, for whatever reason, she prefers that modern junk, something about she just feels out of place driving in "in that big old truck" and everyone else driving little toodle-around cars --- but, there ain't nothing that ever could get wrong with that "big old truck" that I can't take care of right here at the house.

Also, I think it annoys her that, everywhere she goes, empty-pocket dreamers follow her into the parking lot and want to investigate her truck and "how much do you want for it" and "Man I really like your truck"; she never gets those annoyances in her late model wannabe SUV.

 

Another dumb question:

After a pull the vacuum, what about compressor lubricant ?

Does it stay in the system or does it get sucked out ?

Among my supplies, there is a 5-ounce can "Ester Oil Charge for r134a"

There is also a plastic bottle of Peg Oil or was it Pag Oil; I guess one would have to funnel it in there; maybe pour it in an open line --- but then, wouldn't it get vacuumed back out ?

I always get confused about this oil business and some say "use this" and others will then say "never use that"

 

Pulling a vacuum will not pull out the oil and unless you are replacing a compressor, evap or condenser I dont see the need to add any oil and too much oil is not good either.
If you do use shop air I would replace the system drier to be safe.

I really hate my AC system. Since I put it together it has had 1 leak after another, the laters are getting harder to find even with dye.
Dave ----

 

Thanks.

This may or may not be your problem; but, I have learned this after installing three "GoodYear" mini-split A/C-Heaters in our house = biggest junk I have had in years; and, it doesn't matter what name is on them; they are all made in the same place out of the same junk.

Everyone around here calls them GoodYear heaters as they are good for about a year.

What I have learned is that they are using recycled Aluminum for all the tubing, condensor, evaporater, etc.

The recycled Aluminum has no elasticity and will not come and go with pressure changes so what you end up with is a myriad of tiny fractures and they leak in a million places and just keep getting worse.

Is it possible that your components could be made from recycled Aluminum ?

The last several years, I avoid anything that claims to be recycled or made from recycled materials; paper, plastic, or metal, it just will not hold up to regular use.

 

My system started with the used evap from the truck, junk yard compressor, new condenser, drier, valve and new hoses.
The first few leaks were from me as I for got to tighten up a fitting or 2.
I then had 1 or 2 new o-rings that leaked
Then the compressor went belly up so installed a new one and new evap and drier and flushed the hoses and condenser with new o-rings again.

This last time it lasted for the summer then nothing when I needed it
It was to bright for the black light but I also did not see anything that stood out.
It had a little charge based on the gauge but put 3 cans in it and the last time I used the AC, few weeks ago, it worked so who know now?
Oh I also had to replace the clutch on the junk yard compressor before the compressor went bad.

At this point I almost when to have a shop recharge it and if it fails again take it back and say "FIX IT RIGHT"!
Dave ----

 

This is what I came up with to add the air charge.

 

I had one of those fancy r134a cans laying around ( I have a bad habit of not throwing things away) that had the hose with the built in gauge and the quick connect on the end. I took and cut the hose off close to the can, got a hose barb and hose clamp and put that in the hose, and then threaded in a air fitting to fit my air compressor hose. That is my air fill contraption.

Once you figure out where the leak is and have the system down, you can easily pour in the dye, even if you do not use it. Later on if you get a leak (more like when you get a leak) the dye may make it very apparent where the leak is.

On the oil thing you should not have to add any oil unless you change a major component. Nothing really holds a lot of oil except the compressor.

The type of oil depends on how it was converted. If the old r12 and it's oil was flushed out, and PAG oil was added when it was converted to 134a then you need to use PAG oil. If you got a conversion kit from Walmart or the parts stores, where the oil is usually already in the conversion cans, that is usually ester oil. The ester oil plays nice with the old r12 oil if the old r12 oil is left in the system. PAG oil does not like the old r12 oil, and it also does not like ester oil. So if you are not sure what you have, and you have to replace the compressor, you might need to flush the system. if you have just a minor leak and have to replace a small component, you can just leave what oil is in it.

 

Thanks.

I have found that to be good sense instead of a bad habit; many times, having something around that most would have thrown away has rescued me from various situations and also kept me from having to spend money.

So...., I can get this dye in a bottle such that I can just unscrew the lid and pour it in an open hose ? It won't then get vacuumed out ?

 

Typically dye comes in a small sealed can, premixed with a little refrigerant. It looks like a regular refrigerant can, only smaller. You add it to the system through your manifold set, same as ordinary refrigerant. Usually it is added first after a vacuum evacuation, but it can also be added to a system that is already charged, whether full or partial.

During subsequent vacuum evacuations, the dye remains in the system. Unlike moisture, it doesn't turn to vapor in a vacuum and thus doesn't get extracted. (Oil remains behind in the same manner.)