Vincenza V

The A/C is cool in my Jeep, but the compressor cycles very often. Even in 70-75 degree ambient temp.

I bought a UV dye kit,with a really bright UV light, and I did not see any leaks in the engine compartment, around the a/c system. I checked at night too. The only place I couldn't see was behind the dash obviously, though I looked under it, and around the glove box and didn't see any dye there either.

What can cause this? I didn't see a leak, but when taking the dust cap off the large tube that the accumulator is attached to, I did hear a little sound like when you take a tire valve stem off (pshhhhhstttt).

Don't know if that's normal.

I replaced the dust cap and did the dye, letting it run for ten minutes, I didn't see any signs of leaving with the dust cap on.

drhoward1988

Sounds like you are low on refrigerant. Either that or your expansion valve is toast and its kicking out on head pressure. As far as a leak you need to thoroughly check all of your connection points, conpressor, and condenser coil. That uv dye stuff is overated.. I would recommend having a shop with the proper equipment leak check it for you (should cost around 40-50 bucks) and go from there. That cover, if its on top of the compressor its for your king valves. It should have an o-ring down on it

SeriousOffroad

You got a leak.....

Vincenza V

I think the UV stuff is legit. One of my buddies used to work at a garage and said they used it.

I have also heard the "you have a leak" bit if the compressor cycles frequently, but last time I bought the 134a in bottle, it said I was full.

So either the gauge on the can was off, and I actually was/am low-or the expansion valve might be toast?

I was trying to figure it out on my own, since the compressor, orifice tube, and evaporator core are less than a year old...

djb383

U should have replaced the accumulator/dryer when the other parts were replaced.

djb383

I didn't think the XJ A/c used an expansion valve.....it uses an orifice tube instead, no?

drhoward1988

Cant really trust those garbage gauges...and the uv stuff works fine if you have a large enough leak, but smaller ones it rarely shows. Knowing what pressures each side of your system is running at will help you properly diagnose whats going on. Do you have a friend/relative you can borrow a set of guages from to check?

drhoward1988

It has an expansion valve at the firewall. The small metal rectangular box. Now i couldnt tell you what the newer xjs have. But pre 96 have an expansion valve

djb383

The OP says '99, no expansion valve.

drhoward1988

Ok wasnt sure on newer models. I do mostly commercial service, not automotive. I just know what my year range has because ive worked on them.

SeriousOffroad

My daytime gig is commercial refrigeration, has been for the better part of 20 years.

The leak may be in the evaporator, you won't see it unless remove the entire HVAC box and open it up. A massive leak might show up as oil/dye coming out of the condensate drain (passenger side of the firewall).

Vincenza V

They did do the orifice tube and accumulator at the same time, or my compressor warranty would have been void-I had them do it.

Vincenza V

I was afraid you were going to say that Frank.

I found my receipt from the "Ice Cold Air" chain. I did it in the end of 2012, so it is a little older than I though. 90 day warranty, nice huh?

I like the idea about checking pressure on each side. I don't know anyone with gauges, but I will scour CL.

How hard is the a/c box to get too? PITA?

CCKen

Like SeriousOffroad said, it could be the Evaporator leaking.

If you take your Jeep to a good AC shop they should have an Electronic Leak Detector (sniffer). The sniffer probe is to be placed in the center outlets, place fan in lowest speed, set Mode Selector to Recirculation mode, run engine. If the Evaporoator is leaking, the sniffer will pick up the odor of refrigerant.

The sniffer can also be used in the engine bay.

Don't disassmble the HAVC unit just to see if the Evaporator is leaking

Vincenza V

CCKen-wow, that is high tech! Glad to hear they have that, yeah, not doing exploratory surgery. Too much work without knowing for sure. Thanks guys.