Slow AC leak:

Recently purchased a 2000 XJ.

When I got it the system was empty. Pulled a vacuum on it and it held it fine for hours.

So I tried charging it, once the low side hit 30PSI the compressor came on and cycled. It did that about 2 or 3 times and then never again, after switching out the trinary switch to test and see if it was bad(it was not) I tried jumping power directly to the clutch.

Turns out the clutch was bad. So I switched it with a good ac compressor(from a parts jeep where the system still held a charge). Pulled a vacuum, it held fine. Filled it up, blew cold, got 48* vent temps(same as my other 2000 XJ). Figured the reason the system was empty had something to do with the clutch not working, someone was trying to diagnose it etc.

Well about a week later I got in a drove it after getting my plates. No A/C, system empty. I had used one can with UV dye, got out the black light and could find no evidence of leaking in the engine bay anywhere from any of those connections.

Pulled a vacuum again, still held, refilled with a couple of cans of stop-leak stuff.

That was tuesday. Today while driving around I noticed it wasn't as cold as it should be, connected gauges to low pressure line and found my charge had dropped in half.

So no evidence of UV dye can be seen, and stop leak does not seem to be working.

So I replaced the condensor tonight with a known good one(from the same parts vehicle). replaced the o-rings on the condensor fittings, drier fitting, (compressor o-rings previously replaced), started pulling the line that connects to the dash and after pulling one of them off discovered that some pressure was still left in the system behind it, and that the o-rings looked perfect, so I didn't bother.

So at this point I replaced a bunch of o-rings that visually had nothing wrong with them. The system seems to hold a vacuum just fine, and no UV came out where I could find it.

At this point I'm starting to think the only way I am going to find the leak is with one of the HCFC detectors.

Any other thoughts?

did you check the evaporator, use the black light and glasses on the vents for signs of leaks,

Blacklight the Condensate Drain.

-Upsidedown "L" shaped rubber tube 'bout 2 inch long low on firewall near starter. -(older yrs, probably same on 2000?)

Good Luck,
Orange

YUP. Next step is to checking the evaporator. Which I do not like the idea of. Been very dry here, barely get any condensation these days. Last week was a different story.

I still get some, but its harder to see on the driveway in the dark with a UV light.

orange said:

Blacklight the Condensate Drain.

-Upsidedown "L" shaped rubber tube 'bout 2 inch long low on firewall near starter. -(older yrs, probably same on 2000?)

Good Luck,
Orange

Click to expand...

Second on that one, took a while for it show up there but eventually it did once it got real humid. I wonder if spraying some water mist into the vents might help it along some.

RichP said:

Second on that one, took a while for it show up there but eventually it did once it got real humid. I wonder if spraying some water mist into the vents might help it along some.

Click to expand...

Thats what I did, well, into the air intake area.

Then went out for a drive. Came back and parked downhill on my driveway, got just a few drops of water out of the drain, blotted them up with a paper towel.

Took that inside, closed the garage door, and looked at it, it was very subtle, but you could see traces of the UV dye on the paper towel.

So I guess I need to replace an evaporator. Dangit. Maybe I would find some o-ring if I just pulled it, but I would rather not risk it having to pull the dash again to find that wasn't the issue.

Off to the search I go for an evap replacement.

zluster said:

So I guess I need to replace an evaporator. Dangit. Maybe I would find some o-ring if I just pulled it, but I would rather not risk it having to pull the dash again to find that wasn't the issue.

Off to the search I go for an evap replacement.

Click to expand...

There are no connections in the under dash/evaporator. It is your evaporator. Evaporator leaks are a virtual guarantee on XJs along with virtually all Chrysler cars and trucks. It's just the way things are.

BTW, stop using A/C stop leak! You're creating issues down the road by using it.

bottleworks said:

There are no connections in the under dash/evaporator. It is your evaporator. Evaporator leaks are a virtual guarantee on XJs along with virtually all Chrysler cars and trucks. It's just the way things are.

BTW, stop using A/C stop leak! You're creating issues down the road by using it.

Click to expand...

Yup, after looking into it I see that it is one unit. I was expecting an expansion valve to be in the box like many other AC systems. appears the expansion valve in integrated into the line leading into the evaporator.

While the evaporator failure is not uncommon it is the first one I have had out of 15 or so XJ's.

Plus, its just way too hot outside to pull the dash right now. Ugh.

I will probably do an AC flush at the same time its off to remove any top leak in the system now.

Who makes the best replacement ? sure not going to use OEM on this if I do decide to do it.

A 2000 XJ doesn't use an expansion valve, it uses an orifice tube. IIRC, it's located in the line that runs near the passenger side motor mount.

bottleworks said:

A 2000 XJ doesn't use an expansion valve, it uses an orifice tube. IIRC, it's located in the line that runs near the passenger side motor mount.

Click to expand...

Ok, ya got me. I called it an expansion valve instead of an orifice tube.

One last possible- get under the XJ and look UP with the blacklight, (night!). MIGHT be condensation off of cold pipes etc. with a leak, in the engine compartment, and leaving a trail with the fan blowing stuff around. Maybe a trail at drain.
Also shine the blacklight into the vents inside the cabin, as mentioned by jsolorza.

Just trying to confirm, for darn sure, before a dash pull.

Also check some of the write up - seems its suggested to change the heater core while in there, as its old too.

Good Luck,
Orange

orange said:

One last possible- get under the XJ and look UP with the blacklight, (night!). MIGHT be condensation off of cold pipes etc. with a leak, in the engine compartment, and leaving a trail with the fan blowing stuff around. Maybe a trail at drain.
Also shine the blacklight into the vents inside the cabin, as mentioned by jsolorza.

Just trying to confirm, for darn sure, before a dash pull.

Also check some of the write up - seems its suggested to change the heater core while in there, as its old too.

Good Luck,
Orange

Click to expand...

I know for sure the water I blotted up with the paper towel came from the drain, I watched it drain out. No other condensation on any of the lines at the time I did that test. Plus, I already checked all the other places throughly on round one with the UV dye.

Couldn't see anything off down the vents with the light.

But I hear ya, at this point I don't see what else it can be. Tomorrow will be fun, I haven't pulled a 97+ dash yet so it will be a learning curve.

There is a thread on here with step by step with pics, use zip lock bags to keep the screws and such in order.

http://www.naxja.org/forum/showthread.php?t=930897&highlight=evaporator
and
http://www.naxja.org/forum/showthread.php?t=963504&highlight=replacement+seats

I've also got a PDF from somewhere. I thought this was easier than banging out u-joints with 150k+ miles on them.

I didn't pull the steering wheel, was able to pivot the dash skeleton. Took me maybe 10-11 hours (about the same time as the dealer quoted the shop tech needing). I probably burned 1-2 hours trying to find a couple of nuts/bolts I dropped. Be careful with the firewall nuts securing the hvac box.

If you can find an extra set of hands, they're best used removing the hvac box. I did it alone, but it would have been much easier with help.