A/C leak finding

[Tynee]

I posted the same ? over on '88 to '98 (since the prob. is on my '93) w/ no replies, so I thought I would try here.

Anybody know a good method for finding where your A/C system is losing refirigerant? I shot a can of 134 in last week, the A/C blew COLD, next day it blew hot again.

[StingRay]

The first thing is to look for oil at any of the fittings, on the compressor, hoses and cores. If that doesn't work ( it should with a leak that big) then a sonic tester that listens for leaks is next step followed by a dye injected into the system then a black light is used to make the dye flouresce. If none of those work it usually means pulling the cores and pressurizing and dunk testing along with replacing hoses and other expensive stuff in a process of elimination.

[dtlilly]

The EPA frowns upon anyone without the proper license to work on A/C systems.

You really need a gauge set to see what the system is doing. An A/C recycler and vacuum pump are your next tools/equipment you might need.

They do sell a "inject-a-dye" canister, that will blead lime green at the leak. But from past experience, I'd stay away from that, because you can never flush 100% of the dye out, and it tends to "gum" up the system.

You might only need an O-ring set, high/low pressure hoses, accumulator, condensor, pump, expansion valve, etc... depending what the gauges say and your system symptions.

The process of elimination method is for rookies.

[chickenwing]

Looking for oil on refridgerant lines is a valid troubleshooting technique. I do agree r-12 systems should be recovered prior to opening. Never used a dye kit. Had access to a "sniffer".

[Tynee]

Perhaps the process of elimination method is for rookies who have an educated guess, and don't want to spend a fortune on: A) tools they will never use again, or B) a professional with a liscence.

The system has alrady been converted to 134a.

Thanks for your input gentlemen.

[chickenwing]

Check out your local library. They may have books that are... pre-ozone friendly. I have one that details putting your system in vacume using the vehicles compressor. When you think you find your leak you can check it by pressurizing it. Just need to fab up a fitting for a gauge so you can moniter the leak down. Sorry, don't have a stat on how much pressure to use.

[dtlilly]

I used to co-own a repair shop in Memphis, my partner now moved in to a better shop in "Old Town" Olive Branch MS. About 40% of the A/C work we did, were from driveway jack-legs that wanted to save a buck. They usually had $100 or $200 in the deal before bringing it to a licensed professional with the correct tools for the job. A lot of the time they left the shop paying $400-$800. We used to have a lot of area shops that when they couldn't fix the problem, we could.

Go ahead and get an attitude! I've dealt with pleanty that thought they knew what they were doing. You want to do A/C work? Get yourself a set of gauges and learn how to use them. Once you know what the needles are reading/doing, come back here, maybe I'll help you.

[StingRay]

Don I stated the process of elimination as a last and dye as a second last choice. I am no pro but I have a very good friend in the A/C business and I have spent the last 20 years hanging around there. I am also an engineering technologist with extensive education in HVAC design. When traditional methods fail dyes and even process of eliminatoin get called upon. It only happens with elusive pin holes or leaks that are intermitant and can't be easily found. I have watched my buddy tear an entire HVAC system apart looking for an elusive leak and end up resorting to replacing an evap core that he thought might have an intermitant leak yet wouldn't show up even in a dunk tank. When the customer wants the car fixed and all other avenues have been exhausted it's the only way. My friend is highly respected and gets called upon by technicians all over the province for advice including instructors at the local tech school. I would tend to disagree with process of elimination being only for rookies. In many cases in many professions it is sometimes the easiest and most cost effective method when the other traditional diagnostic methods fail. It does however get used all to often by lazy technicians who use it as a method of first resort and then bill the customer for a bunch of useless parts and labor. I personally have a car that leaks 134 litterally one molecule at a time. It takes more than a year to leak down far enough for it to lose effectiveness. It's a tough leak to find in a dirty engine compartment. Yes we found it but it wasn't a five minute job.

[Tynee]

Ahhh, the classic downfall of the net. Impossible to tell the tone of the conversation. Please don't jump to the conclusion that I am "getting an attitude" because I present the opposite of your opinion. I am not the one who jumped in with both feet and started name-calling:

"The process of elimination method is for rookies."

As for "thinking I know what I am doing," please don't misunderstand. I know when I am in over my head. That's when I stop, step back, and ask questions. Kinda the way I did when I decided to start this thread.

If, after gathering more information than I currently have, I decide I am still in over my head, I will either take the truck to a shop and pay outrageous labor rates, or simply not fix the A/C. The entire Idea of asking this question is that I know people spend $800+ on A/C work, and it wouldn't make much sense on a $2100 truck. At this point, I have a total of 10 minutes and $6 worth of 134a invested. If I can find an O-ring that needs to be replaced (for example) I'll have less than $20 in the A/C repair. Not bad for a "driveway jack-leg."

[flip66]

Originally Posted by dtlilly

They do sell a "inject-a-dye" canister, that will blead lime green at the leak. But from past experience, I'd stay away from that, because you can never flush 100% of the dye out, and it tends to "gum" up the system.

Do not use the dye you get at a parts store it clogged my system up and I had to evac and recharge.

[70GMCer]

Here's my 3 cents worth. Been in the HVAC field over 35 years, so a close friend of mine ask me to find a leak in his Jeep AC unit. I normally don't work on cars, but gave it a shot. All I did was put in 200 PSI of nitrogen in the system. Bingo, we heard the leak right away. Couldn't fix it though, was the evap. unit. Anyway, never use any dye. It messes everything up......

[Tynee]

Again, thanks for the input, fellas