A/C Troubleshooting Thread

Hello,

I have an '01 XJ Limited that the A/C has been slow leaking out since I bought it at a used car lot.

It takes a week or two to completely leak down to the point where low pressure cut off cycles the compressor on and off, and I can put another can of R134a in and it will blow cool as can be once more.

I put 2 cans of NAPA's R134a w/ Dye in the system, bought a UV light, checked the whole "viewable" system in the dark several times. Nothing.

Bought a leak detector from Harbor Freight (rather than pay a shop $80 to diagnose) and charged the system, ran it, and it would alert slightly when I stuck the probe down the defroster, and the drain tube, but it also seemed to be pretty sensitive to temperatures and moisture.

My question is this: Am I Testing the Evap Wrong with the Leak Detector?

I just wanted to make sure that was the problem before I ripped off the dash and threw parts at the issue....

Thanks for anyone that has done this troubleshooting....

Try this leak check:

(1) Position the vehicle in a wind-free work area. This will aid in detecting small leaks.

(2) Bring the refrigerant system up to operating temperature and pressure. This is done by allowing the engine to run with the air conditioning system turned on for five minutes.

(3) With the engine not running, use a electronic R-134a leak detector and search for leaks. Because R-134a refrigerant is heavier than air, the leak detector probe should be moved slowly along the bottom side of all refrigerant lines, connector fittings and components.

(4) To inspect the evaporator coil for leaks, insert the electronic leak detector probe into the center instrument panel outlet. Set the blower motor switch to the lowest speed position, and the mode control switch in the recirculation mode.

Well, I did my evaporator coil over the weekend and 4 days later, I believe I have correctly solved the issue. It was one heck of a job, but living in Florida, A/C is a must.

I believe I did it on the last "cool" weekend of the year too, as this week temps are already in the high 70's, low 80's.

I bought all of my parts from Advance Auto Parts due to their extensive coupon codes (saved a ton of $$) except the heater core, as I saw a few bad reviews on the one they sell. I bought the heater core from Napa and it fit perfectly as designed. (I replaced it as I didn't want to ever pull the dash apart this decade again)

I bought a Vacuum pump from Harbor Freight a few months ago on sale for $50 dollars, which in my mind, was a steal! It pulled the required 30in/Hg and vacuumed the system down.

During the install, I replaced the O-Rings, Accumulator, and Schraeder valves to alleviate any issues as well, as a can of R-134a is now $14!!!!! When did the price of R134a Double/Triple?!?!

Also during the install, since the system was apart and changing out pieces, according to the factory manual (when changing out evaps, compressors, accumulator, etc you have to re-add more oil) I added the 3.5-4oz of PAG100 oil that had the UV dye in the oil. This was the best option (to me) as it didn't appear that I would be diluting the system with just dye. This way, if I ever have a leak in the future, it will be BRIGHT UV!!! I was able to purchase the oil/dye mix at Napa as well.

Everything is blowing ICE cold and I've been driving it to work all week, and by now, the coolant would have leaked out or been causing the compressor to cycle. It was a relatively clean job and my dad even helped and kept me sane during this endeavor. I estimate it took about 12-13 hours, part of that was just figuring all the connections to dissasemble, etc. We ended up taking the entire dash out (pulled the steering column, wasn't that hard) for ease and to ensure I didn't break anything. I have a XJ limited and my interior is the still MINT as the previous owner didn't trash it.

Any questions, just ask. It's still fresh in my mind from the weekend.

I also need some advice with my AC, or more how to fix my AC misadventures. I have a 97 XJ. At the end of last summer I started to get a bizarre squealing/ belt squeak that would stop shortly after start up. It was hard to tell where it was coming from, until a few days later when the AC compressor seized up while I was driving. This roasted off the serpentine belt and messed up the harmonic balancer. At the time the only concern was getting my daily driver running again. I replaced the compressor (I couldn't find a bypass pulley anywhere close at the time), belt, and harmonic balancer. I did have to open the system (obviously) to replace the compressor, but at the time I lived in a state where it requires a license to purchase R134. Now its spring and I wanted AC again. I purchased a fill hose with a gauge and two 11oz cans of R134 with a desiccant additive. I started running the AC and very quickly I was up to 65psi on the low side. This was within 30 seconds. This is in the red on my gauge. I'm a little lost since I opened the system, but now it only took maybe a quarter can to get to that point.

I know that there are many things I did wrong here. First being not finding out more about what I was doing before I started. Understand that I'm not as much of blithering idiot as this post makes me sound. My focus was on getting my only vehicle running again, and cheaply since I had just moved to a new state and started a new job. Now however I'm just trying to fix previous mistakes without doing any more damage. Any advice would be much appreciated.

Never mind. I noticed the clutch wasn't engaging and went spark chasing. It was just a blown fuse for the compressor clutch. Replaced and finished charging. It works fine now.

Feimer,

Glad you figured it out, but as you pointed out, there were quite a few things you might have done wrong.

When you replaced the compressor, did you add oil or did the compressor come with oil installed? Anytime you replace major A/C components, you must add additional oil. There is a chart with the shop manual that describes how much oil you should add for each part.

I would recommend after you have done all this that you have the system Vacuumed and recharged again as you have moisture in the system and it was never pulled down to the appropriate 30 inches of mercury. I hate the idea of moisture in the system damaging parts, etc from the inside, as well as the system will not run to full potential.