Good Afternoon All,
I have one that seems to be puzzling me right now. I have a 1999 Cherokee Sport with the 4.0L engine, and today I have discovered that I may have some trouble with my A/C. Today has been the hottest day so far this year in Northeast Tennessee, and I was out doing some work on the Jeep today and noticed when I turned my climate control **** over to max/ac that the air coming out of the vents was none too cool. Upon further investigation, I determined that the electric cooling fan for the radiator was cycling like normal when I turned on the A/C, but watching the front of the compressor, the clutch for the compressor did not seem to be engaging. I tried cycling the system on and off a couple of times, but nothing changed. I decided that there could possibly be a blown fuse or relay, but upon switch the 20amp fuse for the a/c clutch with another and switching the relay with my fog lamp relay, that neither was blown. I am wondering does anyone know if these Jeeps will not cycle the compressor clutch if the refrigerant is low? Or does anyone know anything that I should check in order to determine what could be wrong? Any suggestions are greatly appreciated!

 

I believe the AC has a failsafe built into it to prevent the compressor clutch from engaging if your refrigerant level is low, to prevent damage. Your system may just need to be recharged.

 

Update-I just went back out and started the Jeep, to see if the a/c would come on. When I turned the system on, it came on and the clutch kicked in, but it seemed slow at first and then sped up. I then felt of the air coming out of the vents and it was blowing cold. While the compressor was engaged, I reved the engine just a little bit, and it sounded as if I have birds living under my hood. Could it be possible that the compressor clutch is failing, therefore it is pulling strain on something causing it to squil?

 

belt squeel is very very common with the jeeps. Tighten it or get a new belt. You may be low on freon. There may have been just low enough pressure to not trip the pressure switch to allow the compressor to run and then after you ran the engine it heated the system enough to raise the pressure. Either add some on your own or get it serviced.

 

I have an 01 Sport with an a/c problem. But I have gotten the help here on the forum. When the motor is cold the a/c works as it should. Compressor kicks on and off. But when it gets hot the compressor stops cycling all together. the electric fan is operated by the computer. Basically when pressure builds the switch tells computer to turn on fan to reduce pressure. So if the fan doesn't work then I would try this switch. It is just behind the compressor on one of the lines. That's what mine was doing anyway. Good luck

 

From what I can tell, wheather or not the a/c clutch actually engages, the electric fan is running just like the a/c clutch is engaged. After the engine had cooled and I tried it again, the clutch engaged and the fan ran, and the air was cold. While the engine was sitting at idle, their wasn't any squeel, but when I reved the engine a bit, I recieved the squeel.I turned the ignition off and restarted it all again, and the clutch did not engage, along with the squeel being gone. I am thinking I may have a couple of problems. Possiblly, I have a belt that is not tight enough, hence causing the squeel when the compressor kicks in, and as far as the clutch not engaging at all times, I am thinking maybe it is low on refrigerant. When the clutch is engaged it doesn't seem like there is any squeel or scraping of metal near the a/c the squeel seems to develop near the power steering pump side of the belting system.

 

So today, I have done as everyone said, I jumpered the wires for the pressure switches one at a time. I did not see any different results, however, I did notice that my a/c compressor clutch will stay engaged sitting at idle on the driveway for as long as you would like it to stay there. On the inside of the vehicle, the air coming out of the vents is nice and cold, but the minute you start driving the vehicle, the clutch will stay engaged for maybe a couple of minutes and then the air coming out of the vents goes warm. I have then returned to my driveway and attempted to see if the clutch would engage at idle again, but it will not. Could this be related to not having enough refridgerant or is it something else?

 

A/c compressor / electric fan has me stumped. When I purchased the Jeep the electric fan was seized and the fuse was blown. Replaced the fan and fuse and turned the A/c on and the fan came on as it should. Did some other work on the Jeep and then decided to test the fan one more time to ensure it was coming on when the A/c was on. Turned the A/c on and the fan didn’t come on.

I realized that the a/c compressor was not engaging anymore. Compressor moved freely by hand and will engage when jumped straight to the battery. When jumped a/c blows cold, but electric fan will not turn on.

I have checked all fuses and swapped relays with the foglamp relay which is identical to the a/c compressor relay. I checked the connector supply power to the compressor and it is showing no voltage.

I had always noticed that the compressor would engage and disengage occasionally with the a/c running . I assumed I was low on Freon so I bought a recharge kit. Following the instructions on the kit if the compressor was not running charge with a half bottle and then check the pressure again. The compressor never kicked on. I decided to jump the compressor with the gauge connected so I could get a reading. The gauge started completely spiked and then eventually ended on about 60psi and held steady which is right in the red overcharge area on the gauge.

So now I am assuming I was never low on Freon and the half bottle I put in just overcharged my system.

Why is my compressor not coming on? Mechanically everything appears to be functioning. The compressor comes on when jumped to the battery. If my process of jumping the compressor and taking a reading is correct then I was never low on Freon.

It appears that the compressor is just not getting the signal to turn on? What controls that? I am also assuming that since the electric fan is not turning on that whatever controls the compressor also controls the electric fan. I thought that when I jumped the compressor the fan would kick on, but that’s not the case.

Also how do I safely remove Freon from the system?

 

any luck finding a solution? I have a similar problem. The switch in the cabin starts blowing air but I don't here the AC clutch engage and the aux fan doesn't turn on.

Also, I hear/feel the AC and Aux Fan relays click when pop them into the Power Distribution Block so I think the relays are good.

When I put power through the relay pins I hear the AC clutch engage. But I can no longer get the Aux fan to turn on, whereas I was able to do that a few months back. Probably separate issue for the fan, but still all sort of related.

Let us know if you figured anything out.

 

Just in case you are still trying to figure out your issue, I may have a solution. This sounds like what was happening to mine, "I had it recharged, AC would work for a lil while, then start blowing hot air." The problem is the the magnetic clutch and the clutch air gap. When the engine and the clutch warm up, the clutch air gap becomes to big for the magnet to successfully engage the clutch. This is normally a sign of a worn clutch.

Simplest solution is to remove the pully, and to remove a shim from the clutch which would reduce the clutch air gap, resolving your problem. Do a lil googling on this and you should be able to read more about how to solve the issue.

 

I am having the same issue no fan and no clutch. What fuse should I check? Any help would be appreciated.

 

removing one of the 2 clutch shims did the trick for me---was having exact same issues. --can be done without removing the belt!

 

NO clutch or fan working? I hit the compressor with a rubber mallet and the clutch didn't engage. Saw a youtube video where that was the case when shim needed removed. didn't have the chance to check if I could spin the clutch by hand yet.

 

For me, the AC would work when the jeep was cold but once heated up the compressor would fail to engage (the air would turn warm). Removing the shim, corrected the issue and i have cold AC again.

 

I did the same to my 1996, has worked good for two seasons so far.