So who knows about AC??

My 2000 sport's AC doesnt work anymore, not sure what happend to it, yesterday was the first time i ran the AC in about a month.

Either way I discovered that the AC's clutch was not engaging when the dial in the cab was flipped to "AC".
I tested the clutch and it worked fine after i hooked a direct 12v line to it.
So I must have a bad switch or bad wires somewhere in my Jeep.

I thought about running my own line with a toggle switch in the cab. How ever I was wondering if I left the AC in the ON position long enough, will it explode the lines, or does it have an internal shut off mechanism to prevent this from happening?

it probably got low enough of freon so now the pressure is low and it wont ground the cycling switch. being that your jeep is a 2000, i would say its probably time for an evaporator

like he said, mine did the same thing in my 95 when i replaced the whole system and as soon as i put freon in it the clutch kicked on automaticlly and started to cool the cab. Another thing is that u might want to check the fuse or the wire continuity to make sure theres power enguageing the clutch. Hope it helps

seabass1858 said:

like he said, mine did the same thing in my 95 when i replaced the whole system and as soon as i put freon in it the clutch kicked on automaticlly and started to cool the cab. Another thing is that u might want to check the fuse or the wire continuity to make sure theres power enguageing the clutch. Hope it helps

Click to expand...

Checked the fuse first thing. Now im moving on to the continuity tester...

X2 on the evap. Although some may cringe (without checking with a gauge set first) a quick check would be to add a can of R134, perhaps with the dye. (A gauge set would tell you if the pressure is getting too low, low side has to be a minimum of about 30psi or the clutch will cut out) There is an evap drain hose on the passenger side of the firewall; looks like about a 3 inch long black tube with the end facing the ground. After running it for a few days, with the clutch working, if the water coming out glows green under a blacklight from the dye, its the evap. thats bad.

Well the AC seemed to be running cold even in the summer. If it was low on r134 wouldnt it be functioning poorly?

It's time to stop all the guessing...
Since the compressor clutch engages when 12V is applied that verifies the clutch mechanism is still good....
You should next check the low temperature/pressure switch on top of the accumulator drier (passenger side) against the firewall... Remove the connector and check across the pins of the temperature switch; you should read continuity... If not... either the switch is bad or the system is low on refrigerant due to a leak in the system...
Check system pressure with a set of refrigerant gauges... System pressure should be about 110psi with compressor off.... If it is less than 90 psi; you have a system leak that should be fixed.....

I had the same problem a couple years ago. Turned out to be low charge(I have gauges, so that was the first thing I checked.)

Here's what I did. I cheated. Changing the Evap. coil requires pulling the dash, and I'm lazy. I bought a can of system sealant(you can get it a Checker/Autozone/etc. It's cheap) Installed the sealant, charged the system, and drove it for 40 minutes to let it work. I had to top it off 3 months later, and it's apparently stopped leaking now.

Now here's the bad news. Check your system before you try this. Really! If the system pressure has dropped below atmospheric(it could have actually pulled a vacuum while you had the compresser hard-wired "on") or it's been empty/discharged for any length of time(not as likely, you said it was working recently) you could have pulled humid air into the system. If there is any doubt about weather or not there's air(and water vapor) in the system, DO NOT USE SEALANT. All types of sealant react with moisture in the air to harden. If there's any free moisture in the system, all the sealant will clog up in the desiccant pouch. Then you need a new accumulator.(and you'll still have a leak.)

I got away with it because
A) I knew the system pressure never dropped below 25 PSI on mine,
and B) On the really bad days here, the humidity gets up around 25%

You live in Indiana, right? (humidity central?)

First things first.... find out the status of the system by checking the pressure..... DONOT guess and add refrigerant..... or sealant....
The A/C system on our Jeep only holds 1.25lbs of R134a....; which equates to 1.5 12oz cans.... That amount is measured when the system is TOTALLY empty under a vacuum of 29.7" Hg.
Overcharging the system could cause damage to the compressor....

IF by some chance the system is almost empty due to a substantial leak; there is a good chance that moisture has been pulled into the system when you ran the compressor (as previously posted above); you should not add refrigerant until the leak is fixed properly and a vacuum is drawn on the system and the system is swept with nitrogen to remove the moisture.

Properly means... locating the leak; replacing the O ring, condensor, evaporator or repairing a hole in the line... Whatever is causing the leak.

Not to hijack this thread but I have a similar problem. AC worked saturday then didn't on Sunday. Switch wasn't working to turn on the AC clutch but when I jump the switch it runs fine but doesn't cool. I checked over the whole system and no leaks (put dye in it two months ago).
Any ideas? 89 renix 4.0

Lostman said:

Not to hijack this thread but I have a similar problem. AC worked saturday then didn't on Sunday. Switch wasn't working to turn on the AC clutch but when I jump the switch it runs fine but doesn't cool. I checked over the whole system and no leaks (put dye in it two months ago).
Any ideas? 89 renix 4.0

Click to expand...

You have a slow leak that is not showing up with dye. I had the same problem recently. Had to borrow an electronic leak tester to find the leaks.

Other than the occasional damage to a condensor coil caused by rocks and road debris...; the most common location to have slow system leaks are compressor shaft seals and O rings in hose connections....

These slow leaks are generally caused by periods of system inactivity.
You can run you A/C during the winter months with assistance from the heater to defog the inside of your windows. Running the A/C for shorts periods will circulate the oil and help keep the rubber seals flexible....

I don't get why it would work fine one day then not the next. even with the compressor running (jumped low switch) it doesn't cool. It was blowing 40 degrees the day before. No sign of leaks or dye. This one has me stumped!