How long for dye to show up in ac?

[Shapeup1]

Last summer there was no cool air coming out, filled up freon, and again this summer the ac is not blowing cold.

My mechanic put in the ultaviolet dye (ya know the one with the black light) and we run the ac a bit but he couldn't find the leak. Suggested I should run it another day to see if we could spot the leak.

He's suggesting maybe ...just put the freon and a sealer and hope for the best.
I really wanted to pinpoint the leak so rather then spending the money just for this summer, I could fix it.

He's asking 170(canadian.) to fill it and put the sealer.

Its a 93 6 cyl. 135 k

[BMR]

If it's a slow leak, it might take a while to show up under the UV light. If it cooled good all last summer, and doesn't this spring, that sounds like a fairly slow leak to me. I'd say run it a few days to a week, and have him check it again with the UV. Once you find the leak, you can make a better decision on how to fix it.

[greg r]

The UV leak test does the best for an oil leak, on the assumption where there's oil there's the refrigerant with it. NOT ALL leaks leak oil. The best leak finder is an electronic leak detector that detects for refrigerant(Freon), and 2nd to that is soap bubbles. Find a mechanic with an electronic leak detector, it's the best way. I have one, they ain't cheap, and now that I've had it for many years I wouldn't have a tool bag without one. Stay away from any and all snake oil additives, sealers, ju-ju, whatever. Your a/c will thank you with years of cold once you get it fixed right.

[budz]

From my experience I've learned that refrigerant can leak from the seals where the a/c lines come together. With the system off for the winter oil does not travel through the system to lubricate the seals.
We've used the additive that is supposed to form a seal when it come in contact with air. The price sounds fair to add the additive and recharge the system. The sealant is designed to seal a leak in the condenser or evaporator not really at the o-ring seals. In a lot of cases it makes sense to give that a try prior to paying for a new cond/evap. The true test is to pull a vacuum with a vacuum pump & see if the pressure (vacuum) holds for the time suggested. If it does it means the leak is small enough to seal with the additive.
Hope that sheds a little light.

Good Luck,
Sold air is a luxury most do not want to live without.

Budz

[greg r]

The true test is to pull a vacuum with a vacuum pump & see if the pressure (vacuum) holds for the time suggested. If it does it means the leak is small enough to seal with the additive.

While that works, I see that as working blind and money down a rat hole. With a leak detector, one can home in on WHERE it's leaking if used right. The evap or condensor, a compressor shaft seal, or maybe something as simple as a line fitting or a hose going bad. Once WHERE is known, then you've got options on what to spend your hard earned bucks on.

[Stillrunning]

You will only see dye where you can see it. If the leak is at the evaporator there is no access to see it. If the leak is on the backside of the condenser there's no way to see it. I second the electronic detector. I would consider replacing all the seals/o-rings, especially if the leak is at the compressor shaft seal - the most likely source on a 15 year old car. If you have a leak from any metal part I would consider the stop leak if $$ is a consideration. You might want to get a quote on compressor replacement and shaft seal replacement. I'm about to replace the shaft seal on another vehicle with a kit for $20.00. Certainly cheaper than the $350+ for a rebuilt. Try http://www.acsource.com/ for repair parts, etc.

[xtremeskier97]

Originally Posted by Stillrunning

You will only see dye where you can see it. If the leak is at the evaporator there is no access to see it. If the leak is on the backside of the condenser there's no way to see it. I second the electronic detector. I would consider replacing all the seals/o-rings, especially if the leak is at the compressor shaft seal - the most likely source on a 15 year old car. If you have a leak from any metal part I would consider the stop leak if $$ is a consideration. You might want to get a quote on compressor replacement and shaft seal replacement. I'm about to replace the shaft seal on another vehicle with a kit for $20.00. Certainly cheaper than the $350+ for a rebuilt. Try http://www.acsource.com/ for repair parts, etc.

Can you point to the kit you are going to use? I cant find one for my V6. Also, any manual on changing the seals out on the compressor? Ive changed ALL the seals on my system except for those on the compressor.

[Stillrunning]

Originally Posted by xtremeskier97

Can you point to the kit you are going to use? I cant find one for my V6.

Phone the 800# and talk to Warren. There is an acsource.com and a .net link which makes the site a little confusing. The parts list on the left side of the page also takes some getting used to.

Also, any manual on changing the seals out on the compressor?

I'm using my FSM, Haynes may show it, acsource may have book. There is a separate listing on acsource for shaft seals and compressor seals. If you can just replace the shaft seal (dynamic seal) that would be easier, but you may need a puller to remove the pulley. I'd do some research first. You will need to pull a vacuum on the system before you re-fill it. Either get a shop to do this or buy a vacuum pump for about $150+. It is also suggested by most references to replace the receiver dryer as well, but if that has already been done then the vacuum pull may be enough. My receiver/dryer from acsource was $12 -Advance Auto = $30, dealer = $65.

Be sure to keep track of lost oil in the system and replace, otherwise you risk ruining the compressor. You'll need references for that too.

[xtremeskier97]

Originally Posted by Stillrunning

I'd do some research first. You will need to pull a vacuum on the system before you re-fill it. Either get a shop to do this or buy a vacuum pump for about $150+. It is also suggested by most references to replace the receiver dryer as well, but if that has already been done then the vacuum pull may be enough. My receiver/dryer from acsource was $12 -Advance Auto = $30, dealer = $65.

Be sure to keep track of lost oil in the system and replace, otherwise you risk ruining the compressor. You'll need references for that too.

Yeah, Ive done it all before, a few times! My dad is an a/c technician (industrial) and pulled the vacuum for me last time, but he's in Virginia and Im in Louisiana...so I have a contact that's gonna do it for $30. Ive already replaced all the o-rings in the system, drier, AND expansion valve. Also blew out the evaporator. Just wondering if I should mess with the compressor. May as well since Ive gone this far.

[greg r]

Here is an e-mail from a friend of mine, we both worked in the a/c end of things, who worked extensively in the R&D and service of mobile HVAC systems. He also taught it and engine systems for many years:

Thanks for the compliments, it WAS a great show and MUCH more of a success than we had planned for!

I'd NEVER put dye in any system. It will NOT work in R-134a applications because of MANY reasons, dye is all marketing bullshit! And it never worked worth a shit in R-12 stuff anyway, if ya spotted an oil stain, ya had a leak, no dye needed for that!

The ONLY effective electronic leak detection system is the one that uses the "heated diode" technology developed by GE back in the day and then sold off to Yokogawa. Corona discharge tools simply will NOT work on R-134a I don't care what the manufacturer says! I've done EXTENSIVE testing on this subject for MANY years during R-134a R&D. The only other detector I'd ever consider using is made by Leybold Inficon but those are lab instruments which can be set up for field use but are way too expensive for any shop to own. We used those for "standards" by which all other detectors were compared. The Yokogawa instrument can be calibrated at each use by working with a calibrated "leak" standard.

Dye will ONLY work if OIL is carrying the dye "outside"! In the case of R-134a and PAG, if any oil exits, it evaporates almost as readily as contact cleaner! But in most all leak points, NO oil will leak UNLESS the leak point is oil flooded and it blows out, then ya don't need nothin' but eyeballs to see it!

That "sealant" shit is responsible for DESTROYING any recovery/recycling machine in shops today, most shops will NOT recover without first trapping a sample inna "identification" machine. If that sealant gets inside, the machine is fucked! Why use snakeoil??? Why not just find the leak and fix it! You should see what that sealant shit does to the inside of a compressor!!!!

Leak detection is the NUMBER ONE issue in mobile HVAC service. Very few shops do it right, they just dump in dye, charge the customer, tell 'em to go away for two weeks, and if they DO come back, then blow smoke up their ass and throw parts at it until the customer can't stand anymore!

I wrote the "official" leak detection position program for ZEXEL (worldwide), this was the document used for warranty determination. And it was re-printed/incorporated in ALL of our customer (Nissan, Isuzu, Subaru, Saturn, Freightliner, Volvo, etc.) service bulletins, warranty statements, parts bulletins, service training, etc. The last project I did for Isuzu consisted of a video technical training program for problem analysis and leak detection, that paper was the basis for the video.

I've used the dye over many years in large a/c and refrigeration systems, and like him I've come to the conclusion that it's money down a rat hole for the money invested in it. Sealers, dehydrants, dyes; they've all come and gone, nothing replaces good old fashioned workmanship.