Before going to the AC shop to have your Freon pressure checked you can do a quick check of the AC electrical system to see if the compressor works.

See pic.

Remove the electrical connector off the Low Pressure Cycling Switch on top of the AC Accumulator and jumper the two pin cavities with a small paperclip of a piece if 20 gauge wire.

Turn the AC mode selector to max air (recirc), turn blower to any setting. Start the Jeep. The compressor should engage. If it does, only run it long enough to see if it works. If the Freon is low, or empty, there will be little or no lubricant going through the compressor and it will damage if if run too long.

If it doesn't engage there an electrical problem in the HVAC electrical system that needs to be corrected.

 

A good AC shop should have a sniffer that can be used to see if the Evaporator is leaking.

If they can charge the Freon system enough to get the compressor to engage, they can use the sniffer at the center outlets above the radio to 'sniff' for Freon. If they do service the Freon they should use Freon with dye in it that can be seen with a black lght.

The AC mode selector must be selected to setting #10 (see pic) and the fan set to its lowest setting. The sniffer probe is inserted in the outlet. If Freon is detected, the Evaporator is probably leaking. If not, they should use their black light to look around the engine bay for a leak (they should do it anyway).

 

Do like CCKen said. Don't spend anymore money getting parts for it until you have it checked out. If you are lucky it's something minor like a o-ring or a hose leaking.

 

There's a way to check Freon without a pressure test or taking it to a shop. There's a part in your A/C system called a 'DRYER. On our vehicles, it's right underneath the compressor about half way down the block itself. It's easy to identify as it resembles one of those small propane tanks you use with a Coleman camp stove, only it's black. On the top of this dryer is a small [ less than 1/4 " ] sight glass. You'll have to clean off top of dryer to remove accumulated grease and you'll see it. Like I said it's small but unmistakable because once you clean it, it's shiny. If you see bubbles in there [ usually 1 big long one ] You need Freon. Use a flashlight and you'll see it fine.

 

The OP has a '98 XJ. Doesn't have that Rube Goldberg stuff.

Right Church, wrong pew.

 

The sight glass was the best diagnostic tool you could ever wish for.

In a vast plot to get into owner's pockets even deeper, they were eliminated by the industry.

The rich get richer and the poor get poorer.

 

I have a '95 so it's not 'Rube Goldberg' it's probably an older system than in '98. Doesn't matter, as long as it's cold I don't care if it's made with sticks and rocks.

 

The mechanic I'll take the Yeep to is a family friend and knowing him, he'll check the system for free, so it's not a lot of trouble for me. I'm just going to keep my fingers crossed that it's just something easy to replace and won't be a big deal. And if it is the evaporator, maybe I will see about finding a buddy who would be willing to help me replace it.

 

I didn't think of this earlier, but I probably will have to get my heater core replaced before next winter. It doesn't drip out in passenger floor board, the defrost works perfectly as it should, and it still blows hot, but whenever I run the heat, it smells like maple syrup in the cab, so I'm pretty sure the heater core has a small leak too. So if that's true I would probably just replace the evap core while I'm at it.

 

I'm sorry, I didn't know.

 

That's cool CC. We're all just trying to help the guy save some money and get his A/C working before it starts hitting 90 degrees, if that day ever comes!!!

 

Well if I get the diagnosis and it doesn't look good, are there any CF members in the Cincinnati/N. KY area who've worked on an evaporator core replacement before? I'd pay anyone willing with a case of brew of their choice!

 

I don't mean to hijack the thread, but what does it mean if the compressor turns on and it doesn't blow cold? I understand that the compressor won't turn on if there's no pressure in the system; I had that issue last year, took it to a shop, they lubricated the system and filled it with Freon, it stopped blowing cold a few months later so they replaced the line ports and recharged it. In both cases they told me I didn't have any leaks, and I haven't used it since until about a week ago. I tried putting one of those recharge kit gages on it but either the gage is broken/clogged or I truly have 0 psi in my A/C system.

Thanks!

Also, last year I was able to find a very detailed DIY thread that walked through a bunch of troubleshooting steps on this forum, now I can't seem to find it with either the search function or in google. Any ideas?

 

I found that removing one of the washers from the AC compressor clutch fixed my AC problem (worked when cold, then blew warm air after running for a while). If the AC is charged, it could be that the compressor clutch is worn out?

 

That's the weirdest A/C "fix" I've ever heard of.

I wonder if they teach that in A/C Tech School?