LIJEEP

Having issues with my AC system on my 2000 XJ. A/C blows hot, I checked the fuse and relay under the hood. I checked the engine harness that connects to the A/C compressor wire and no power is there. I also tried jumping the Low Pressure Accumulator Switch with no luck. Whats next here?

Saudade

Probably low on refrigerant.

You could apply 12v directly to the compressor clutch to make sure it's engaging. Don't run the engine while you're doing this. After that, check your refrigerant. You'll need a set of manifold gauges or take to an AC shop.

LIJEEP

Forgot to mention, I’ve tried jumping the compressor itself as well by using a wire from the compressor wire directly to the battery and had no luck. I think the AC compressor is bad, but why would I get no power from the engine harness with the AC turned on?

Idunno

Repeating one of the clues previously mentioned: Low Refrigerant. Low refrigerant means low pressure. Low pressure switch disables the compressor.

LIJEEP

Low refrigerant would disable a compressor from engaging even with direct power from a extrernal wire connecting from the compressor to the battery?

LIJEEP

Anyone?

Saudade

Low refrigerant should NOT prevent the clutch from engaging if you jump it directly from the battery.

If you have a volt meter, connect it to the wire coming from the engine harness side and ground. Start the engine, turn on the AC with the fan at the lowest setting. You should have system voltage (like 13.5+ V). If not, you may still be low on refrigerant or have some other issue.

The FSM does not give a resistance reading for the clutch coil. You could still check it. (Engine off, clutch lead disconnected. If it's extremely high (like infinite), the coil has an open circuit. If extremely low, like zero, you may have a short. Make sure you check the correct wire, the other side is already ground.

The FSM says to test current draw (amps), so an ammeter would be connected in series with the harness and coil wire. The spec is 2.0 - 3.9 amps at 12.5 volts. If the system voltage is higher than 12.5, you may need to turn on other stuff (like lights, higher fan speed) until the system voltage drops to 12.5

Last thing to try is, again engine off, disconnect the clutch. Jump like you did before, but this time push in on the clutch plate to see if it suddenly engages. If it does, your air gap is too big (lot's of threads on this).

JonRedcorn

If you aren't getting the compressor to kick over with direct power it's most likely the clutch is shot. Same thing happened on mine. Had a bad high pressure switch and then the clutch took a dump. Bought a nice little denso AC compressor and the AC is ice cold now. Also had a leak as well. It was definitely worth fixing. I chased electrical issues the whole time and it was all just simple things that were not working. Make sure if you open the system up that you pull a vacuum on it.

RockyMtn96XJ

Clutches are cheap too. So are the free rental tools at your local parts store (more than likely)
I was in the same situation with my old cummins. Had low freon so I filled it, then the clutch still wouldnt engage. Went with my gut feeling and changed the clutch. AC worked perfect after that.

LIJEEP

Thanks for the replies, I’ve been sick lately. I overhauled the entire AC system. Replaced the compressor, receiver, accumulator, condensor and orfice line. New problem is A/C still blowing warm. The Compressor Clutch kicks on and I filled the system with freon. I have a feeling my evaporator might be clogged...? Any suggestions

RockyMtn96XJ

Did you happen to change the orifice tube with all that? It is a filter for the system and can get clogged.

LIJEEP

Yes thats the line that connects to the firewall and condesnor. The kit came with a brand new one. Whats weird was the line wouldnt get cold after I recharged the system then suddenly it did. I blew out the evaporator with a compressor. My AC clutch kicks on/off every 4 seconds. I used the Autozone freon fill-up tanks. Im thinking I need a legit recharge from a machine?

LIJEEP

Final culprit was too much air in the system without enough freon. I bled the high side until freon pissed out. Those freon cans from the autoparts store arent that great. Between a new compressor and recharge, I now have ice cold air

Saudade

Ah, that's not how you're supposed to do it. You need to draw a vacuum. The vacuum not only expels air, but boils off and expels any moisture. Any moisture trapped inside can change to ice and create a blockage or damage parts. Moisture can also react with the R-134a and cause corrosion.

RockyMtn96XJ

A/C still running good? I would still look into having the system vacuumed and recharged even if its running good so far. Even if your A/C continues to run great, there may still be the moisture and whatnot in the system to cause problems later.
I would hate life if I didn't have A/C right now. Mother nature has graced us with triple digits in the Denver area this week. My A/C is cold and works great, but not when it's 100° and probably 130° in the jeep when I get in it at 4pm to go home.... I REALLY wanna put some heat barrier between the roof board and metal roof, then add some behind the door panels to seal them up better. The ambient heat in the jeep is killing the A/C efficiency, along with whatever heat lingers from above the roof board and in between door panels.