A/C Issue, need some advice

Vehicle is my '00 XJ Sport. Jeep has 182k on it. Did a head swap back in the end of March. A/C hasn't really worked on this Jeep since I purchased it back on Halloween of last year. I went to the parts store today and got 2 cans of 134 and a hose to add it. When I connected the hose to the low pressure side(the fitting right off the filter/drier), it was reading just below the 55 on the gauge within the green section. The compressor clutch is not coming on when you move the selector to any of the A/C settings with the fan on full blast. Is there a way to check if the clutch is still good, or is there something that I am missing to see just why I am not getting cool air, as the clutch is not working?? Thanks for your responses.

Jeff

You can check the clutch coil for about 2 ohms I would guess. Check the fuse. And check to see if 12 volts is reaching the clutch.

Did it still have pressure on the lines?

when the system is not running (clutch disengaged) the high and low sides equalize pressures. If you're seeing 50ish psi on the low side, you're still severely under charged. You should see somewhere between 100-150psi when it's off/ not running.

Try running a constant 12V power source to the clutch and charge it while the clutch is on. This will allow the system to "pull" the refrigerant into the line and slowly charge. The low side pressure you are looking for depends on the ambient temperature outside, but a good estimate is 30-35psi less than the outside temps-- e.g. 50-55psi at 85* ambient temps with the system running on "high" and good airflow through the condenser.

Ok here is what I have found so far. I checked the fuse, its good. I swapped the driving light relay with the clutch relay, nothing. I ran my VOM across the clutch and while I was showing 12V with the key on, AC on, the clutch wasn't clicking, or engaging. I have a strong suspicion that the clutch is out, since all the other checks are showing that the clutch isn't engaging when its energized with 12v. In response to the other question, I didn't hook a gauge up to the high side, just the low side(since the freon hose for adding needs to be on the low side). Since the clutch isnt even engaging, and I am seeing that there is some pressure within the system, should I go check the high side and see just what its showing?? Thanks for the ideas so far.

Jeff

I am also wondering if I add a can of freon, if it is low, the low pressure cut off switch could be activating, preventing the clutch from working either. The hose instructions indicate to add a can of freon, then check the clutch to see if its working, which could be my problem. Just wanting to try and get the best diagnosis here, as the temps are starting to climb and my kiddos don't need to be out in this heat/humidity.

Jeff

I'm not familiar with the 00 model but most all I've seen, the clutch is simply an electro magnet. Check the clutch wire with the connector disconnected with an ohm meter to ground, then the case to battery negative to make sure the case has a good ground.

I usually jump a *fused* (aftermarket in line fuse holder) jumper wire directly from the battery positive to the clutch wire and listen for the clack or clunk when it engages. I've never seen a bad clutch (anything is possible) but have seen the wires between the connector and the clutch broken. Usually some kind of physical damage from a thrown belt or whatever, use a flashlight and look closely where the wire goes around the corner and into the clutch.

I wouldn't add any Freon until I get the compressor running, then add to the low side with the doors open and the fan on high, to around 25 PSI. More Freon doesn't mean more cold as some people think, the pressures have a sweet spot, over filling can damage stuff and really doesn't get it any colder.

I had this happen on a friends 01, we pull the front of the clutch off, cleaned off the rust and put it back together, after fixing that we were able to charge his system and now his vent temps are in the high 30's low 40's.

Also just an FYI the system takes ~1.6 lbs of freon, so be careful not to overcharge it as you can damamge the compressor.

I agree, check the clutch coil and ground with an ohm meter, if the clutch is not open (if it shows several ohms instead high to infinite ohms) and the ground is good, the only remaining reason for a clutch not to engage is the air gap on the front side. The long flat pieces on the face, can be adjusted just by bending them up a little with a screw driver. Not the pro way of adjusting it, but it works. Also make sure you are getting full power to the clutch (see is a battery jumper wire works).

I am going to add a can of freon, since it may just be low enough that the low pressure switch is closed, and then see where it goes from there. All other checks are coming up with no negative results as of right now. I am still looking around for a jumper wire I can go straight to the battery with, instead of through my meter. I will post up once I have more definite results so we know where to proceed to next.

Jeff

Tried to add some freon, no go there. Ran some checks on the clutch and here is what I got:

I have continuity between the two wires going to the clutch. I don't seem to see any voltage coming from the harness to the clutch wiring. Grounds are showing good continuity.

Upon running a continuity check on the clutch, my meter while beeping at me, was showing 0.04 in the ohms. Its an autoranging meter, so I am not quite sure where this reading is measured at. Thoughts now??

Jeff

Don't know about the meter, I hate the digital meters....but .04 if it is ohms, sounds like a shorted clutch (did you try to power it directly from the battery yet???)

The two wires in the harness also sounds like a dead short. Neither is good, if correct.

Buy a couple of feet of wire and an in line fuse holder and package of fuses, 10 amps should be enough, 15 amps way more than enough. Over 20 amps and the wire may melt before the fuse blows.

When the pressure in the can is the same as the pressure in your system, the freon isn't going to move. When the clutch is engaged and the motor is running the low side pressure will go down and you can add some Freon if needed.

There is a trick to adding Freon when the pressure is the same in the system and the Freon can, but I'm not going to tell you until after you test the clutch.

Over filling the compressor can be catastrophic. Some have a built in bypass that pops when it over pressures and makes a heck of racket, some have a mechanical fuse that blows, some just explode and spew freon and oil.

Ran a lead from the + terminal on the battery and nothing. Ran a lead from + and from - on battery and nothing. Im figuring bad clutch. Problem, the clutch is about what a compressor and clutch would be. I haven't shopped Rock Auto yet, but thoughts here?? And after the pressure slightly climbed on the gauge towards the red, I shut the freon off and left it as is. Replace just the clutch or do both the compressor and clutch as a unit??

Jeff

You keep saying two wires? Only one power wire to the clutch as far as I know. The clutch grounds through the case.

Do an ohm check from the case to battery ground.

Do an ohm check from the clutch in wire to the case.

That wire makes a sharp bend at the front of the case and goes behind the pulley. I've seen a thrown belt cut (tear it in two) that wire near the bend.

Also don't trust doing an ohm check though the connector, strip back a little insulation on the wire with a sharp knife after the connector, to make your continuity test. You can tape it over later and seal the tape with a drop of super glue.

Well here is the scoop. There are two wires going into the clutch on the front. One is for a ground, the other for the power. I ran my check through the wire, not the connector. I did try to power the clutch directly from the battery, and I got nothing. Should I just replace the clutch or do the clutch and the compressor?? Clutch and compressor is a tad more than just the clutch. Thoughts??

Jeff

If you open the system to replace the compressor, you are going to need a vacuum pump. Air and moisture inside the system are the enemy.

You really don't know if the compressor is toast or not until you get the clutch working. Something caused the coil (electro magnet) to fail.

Your particular compressor is new to me, but they are all much the same. A couple of snap rings, a bolt and maybe a puller and the clutch is off. You can actually replace just the coil (electro magnet) behind the clutch.

You need a little know how and some experience to recharge the system. You have to be quick on the valves. If the compressor stops at the wrong time and you have more pressure in the system than you do in the can the Freon will flow back into the can. The hoses have to be purged or the air that is in the hoses will end up inside the system (air and moisture are the enemy). You fill the system by weight, the contents of the can (usually multiple cans) until the weight of the contents (of the cans) match the specifications for the system.

Not that complicated, but for a first timer it can be a little tricky. It is a lot easier with the right tools and equipment (which are really expensive).

If it were me I'd pull a clutch off a junk yard compressor and replace the coil in my compressor cluztch and fire it up and see what happens.

I've heard of clutch coils going out, but it is rare in my experience. Many other parts prone to fail before the clutch coil does. It is usually an open wire between the connector and the coil itself that fails, vibration or physical damage. Any part can have a fabrication defect or fail if it gets hot enough.

ihscoutlover said:

Vehicle is my '00 XJ Sport. Jeep has 182k on it. Did a head swap back in the end of March. A/C hasn't really worked on this Jeep since I purchased it back on Halloween of last year. I went to the parts store today and got 2 cans of 134 and a hose to add it. When I connected the hose to the low pressure side(the fitting right off the filter/drier), it was reading just below the 55 on the gauge within the green section. The compressor clutch is not coming on when you move the selector to any of the A/C settings with the fan on full blast. Is there a way to check if the clutch is still good, or is there something that I am missing to see just why I am not getting cool air, as the clutch is not working?? Thanks for your responses.

Jeff

Click to expand...

It is recommended to replace the accumulator, especially on older vehicles, when repairing / recharging the A/C.

I don't think I would attempt another recharge without A/C recharging equipment and gauges. After pulling the compressor and replacing the clutch I wasn't able to obtain a good recharge using an auto parts stores recharge kit .. most appear to be designed to add freon to a partially charged system.

Since it never works and rarely used. I am thinking of removing the A/C, to free up room in the engine compartment.