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Old 04-25-2011, 07:33 PM
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WJ Air Condition Woes Continue

Vehicle: 2003 WJ, 4.0L Engine, Manual A/C System


Ever since I got my Jeep it has had an A/C system issue. First it kept blowing the 15A fuse in the engine bay. I found a short where the wires pass through the metal wire loom next to the head. So I replaced that section of wire and added rubber grommets where the wires go into and out of that metal loom. Then it worked fine for the entire last half of summer.

It has also had the issue where the actuator would change from cold (or heat) to it's middle position. I would have to tap on the temp control knob to get it to go back to where it was suppose to be. So I took the control panel apart, got a new potentiometer, and soldered it in place. That problem was solved.

Now I just noticed the latest problem today as I decided to test the A/C system before it got hot. I turned it on and low and behold, the same 15A fuse was blown. So now I broke out the DMM in the little amount of time I had before it got dark. What I found was rather peculiar.

With the engine on and A/C button pressed on, the resistance from the fused side of the fuse to ground was 0 ohms (short circuit). When I turned the A/C button off, the resistance jumped to 18 ohms.

So my first thought was the relay is bad. So I pulled the relay and measured the resistance from pin 87 to ground. With the engine off, the resistance was 18 ohms. With the engine on, the resistance was 0 ohms (short circuit). Neither of those two measurements mattered if the A/C button was on or off. So with that I concluded the relay is not bad, it's something else down the electrical line.

Does anyone know what would cause a short circuit while the engine is on, but measure fine while the engine is off?

Tomorrow I'm going to disconnect the plug at the A/C compressor and see how it measures. But I'm guessing once that's disconnected, it's going to read open circuit when the engine is on and off. If that's true, that means it's part of the A/C compressor or compressor clutch. Are those parts always the same? Or can one part be replaced without the other?

Ideally I would like to fix this issue without having to take it to the shop to evacuate and recharge my A/C line. Does anyone have any ideas what would cause possibly cause the system to measure 18 ohms with the engine off and 0 ohms with the engine on?
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Old 04-26-2011, 09:45 AM
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Re: WJ Air Condition Woes Continue

When measuring point 87 to ground shows 0 Ohms, or the problem is the compressor clutch solenoid, or more probable the wiring. Have a close look to the wiring at the compressor, maybe a wire is touching the compressor pulley and is making contact to ground this way. If necessary you can change the clutch assy separately from the compressor
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Old 04-26-2011, 02:01 PM
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Re: WJ Air Condition Woes Continue

I did a quick search on the local parts stores and none of them sell the compressor clutch. All they sell is the compressor with the clutch assembly already attached.

After thinking about this last night and today, I've concluded there are 2 possibilities. The first is that something in the clutch assembly is screwed up and only causing a short when it's running. The other possibility (which I think it more likely), is that the A/C compressor clutch wire (somewhere between the relay and clutch) is shorting to another wire and that wire is switched when the engine is on. Then when I turn the engine on, the A/C wire shorts through the other wire to ground. If this is the case, I'l be going straight to the wire channel by the engine head where I had problems earlier.

Waiting for the end of work today is killing me. I just want to go diagnose my problem and figure out what I have to do to fix it.
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Old 04-26-2011, 04:45 PM
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Re: WJ Air Condition Woes Continue

That problem has now been fixed. But I created a couple more in the process.

The problem was indeed caused by two wires shorting together. The wire loom comes out of the channel at the back of the head, behind the head, and along the firewall. WAY behind the head, it melted through the tape, plastic wire loom, and wire insulation. So I wrapped each wire in tape, new wire loom, taped it all up, and secured it way from the hot metal.

New new problems came about while trying to move/unplug everything to get the wires where I could access them. I broke the back back crankcase vent elbow. I already have a new one on order since the auto stores don't stock them.

The other problem was when unplugging the injectors (only had to unplug the back 2). They are old and BRITTLE. I tried to be very careful but I broke both of the little red safety tabs off. Then on one of them, the push "button" part broke when I was pushing on it. So my #5 injector just sits on the plug (the snap is broken).

Anyone have any brilliant ideas on getting that to stay in place? I'm thinking I either zip tie it down or buy a new injector plug and solder it in.
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Old 04-26-2011, 09:04 PM
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Re: WJ Air Condition Woes Continue

Good to hear that you have found the problem with the airco.
Had the same problem, the small red locking tab from injector # 6 broke. Its now hold in place by the bigger red lock only. Its indeed almost impossible to remove the injector connector without breaking the red tabs. Would like to clean all injectors, but donīt want to break all tabs. Would be nice if only the tabs could be changed. Anyone an idea?
Not sure if soldering a new plug on is a good idea. When soldering you make the wire very riggid locally and making it prone to break due to vibration.
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