When I bought my truck a year ago, the A/C didn't work. Refridgerant was empty. I let it got thru the winter (who needs A/C up here in January??) and had it charged by my local wrench in the spring. A/C worked 100% all summer (or seemed to). About a month and a half ago, one a particularly warm day, I turned the A/C on to find warm air. No cold. Nothing. Decided at hte next oil service, I'd have it checked out. Dealer service called me and said that I was empty again. They would fill it and dye it and check it. The "sniffer" found no leaks, neither did the black light. They suggested driving it over the weekend and bringing it back and they would run the black light over it again.
Ideas? It was obviously empty when I bought it. It emptied itself out again which means there's a leak somewhere. But they can't detect anything...

 

Have them check underneath where the Evaporator drain dump is located.

 

You can also remove your blower motor resistor and get a little view of the lower corner of your evaporator. With a small mirror and the black light (mines small) you can get a little look to see if any leaks show up. If there are none you most likely need a compressor.

 

You may have to take to some other shop, as you explained to them it was leaking and had no freon, I suspect they did not do a thorough enough job to find slow leak. As Shovelhead and JBODY suggested, they probably did not check inside cab at evaporator, or outside water drain, or front seal of compressor, or condenser bottom(all common spots often overlooked). Do you know if they did visual check and repair, then evacuated system, and checked for leakdown of vacuum, then partly fill(with dye) to leak check with sniffer and black light, or c/o receiver/dryer, or topped up a/c oil? This will tell you the quality of the repair.

 

Torque,
I was told they did go over it with the sniffer and did mention the evaporator so I assume these items were checked. They spent an hour on it. How much of that work/repair/replacement would be covered under the warranty? Any?

 

Depends on what warranty you have. A couple years ago I fought r-134 leakdown on a few truck. They would be fine for two to six months, but then come in with the charge 1/2 gone. Dyed a few twice, nothing ever showed up. Discussion came up at training and two techs said "compressors" when I brought the subject up. Installed compressors on the problem children and problem was solved. Funny thing is I even pulled the clutch/coil assy off one of them an there was still no die showing, but yet replacing the compressor took care of the prob. I had the same issue this spring. Installed a new compressor and a/c is still working great. It's one he77 of an expensive guess if it's out of pocket, but I've seen quite a bit of success of all other routes of diag have been followed. Another area that comes to mind that can "hide" a leak is the high side line coming off the compressor. It has a foil/fiber sheath around it. Peel that back at the ends and inspect the crimps. I have found those lines leaking too.

 

Some A/C leaks are very hard to detect even with dye. Many leaks only occur with the system running in high load and the dye seems to vanish.
Often a high pressure test with dry nitrogen is the only way to find them. Amazing what a 300 psi test will locate.

My brother had a leak on his dozer A/C system. A nitrogen test determined a couple flexible lines would seep at high pressures.

 

probably evaporater core leak.Had mine replaced a few months ago.The man told me this is very common with the ram-the core was a stocked product!

 

I would call and talk to service manager and explain situation, and take it back in for repair if it is still under warranty. Tell them to thoroughly go over again, especially items mentioned. Warranty will be based on the type of coverage you have. If you wait until it's out of warranty, and problem re-develops afterwards, you'll be on the hook for all of it.

 

I had the same problem with my truck. I had it at the dealer 5 different times because the A/C quit cooling. Each time they checked it, it was low on refridgerant. They put dye in the system to try to find a leak, but never found one. Each time they claimed to have fixed the problem, but about 2 months later it would quit working. During the various times it was at the dealer, they replaced both A/C lines, the evaporator and the compressor. I have had it back for a couple of months now, and it appears the new compressor may have solved the problem. I had to fight them, but each time after the first visit, my extended warrenty covered the repairs. I was even able to get the dealer to cover the $100 deductible since I had to bring it back 4 times after the intial visit. Good luck.

 

I am going to call them today and set up an appointment to have it looked at again to see if any dye has leaked. If they can't find anything, I am going to have to suck it up for now. If by spring it's dry again, i'll bring it back and make a stink then that they should find and fix it for free since the problem was brought to their attention before the warranty ran out.

 

Took it back today. they checked for dye leaks on all external connections and areas and found none. They are at the point now where they believe it is the evaporator wihch they estimated at a $650 job or so parts and labor becuse of what you need to take apart to get to the evaporator. I think I will hold off for now. If the leak doesn't worsen, I can get away with recharging the system once a year (even twice) for a few years before spending that kind of money......

 

I hope that your system is not completely "dry" as you put it. A/C systems that are left exposed to the atmosphere or more importantly "Water" will develop or produce HCL or hydrochloric acid, which will rot your system from the inside out. At minimum, your acumulator/receiver/drier should be replaced. You should also be adding the proper oil with your "charges" Lack of oil will eventually cause your compressor to go kaput.

 

If you really want to know whats leaking, install some florescent die in the system and run it. Park it in a dark place and use a black light. There will be no doubt in your mind what you need to fix, replace, tighten up etc.

Thats how I found my evaporator leak several years ago. I've spent more money on the AC system than any one single thing on the truck. Seems like every 55 to 60 K on the compressor.

My son has my old 96 12V with 264k on it with the original AC system. Its never been touched!

Dave

 

I has been charged properly by the dealer and they did put dye in it and have now checked it over twice with the black light. the only place they cant check is the evaporator without taking the dash apart. I have decided to wait until spring and see where I am. it's not under warranty (mine had a 3-36) so thats not an issue.