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Old 05-24-2010, 09:23 AM
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A/C Clutch Cycle Switch Location?

2003 WJ with I6 engine

OK, my AC hasn't been working. I figured the system needs to be recharged so I go and buy a can of R134a. I turn on the AC and blower to MAX and hook the charging kit up to the low side port....it reads 110psi. With the AC compressor running it should read ~40psi. Seeing as how it's reading MUCH higher than that, I don't think the compressor is engaging.

So I go looking for the AC compressor clutch cycle switch so I can short the wires to keep the compressor engaged. Normally I've seen them next to the evaporator canister (located on passenger side next to low pressure port and battery). There is no connectors around the canister.

Can someone tell me (better yet, profide a picture) of the switch location?

I have one picture my from my buddys 2001 WJ I6. His switch is located on top of the evaporator canister but mine isn't. Obviously something was changed between 2001 and 2003. Any help would be appreciated.

*EDIT* Attached a picture of the evap canister from the 2001 WJ. You can see the connector on top. It's located on the passenger side right next to the battery. This isn't the location on my 2003 Jeep.
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File Type: jpg AC Switch.jpg (88.7 KB, 39 views)
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Old 05-24-2010, 01:20 PM
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Re: A/C Clutch Cycle Switch Location?

hi there.
The switch on your buddy's 2001 is the low pressure switch. on the 2003 the switch is called a pressure transducer and is mounted on the discharge line next to the condenser (on the right side of the condenser from drivers view) it is a 3 wire type switch and it should be serviceable without discharging the refrigerant system, just be carefull as some r134a might slip out.... hope the info helps.
best regards
michael
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Old 05-24-2010, 06:02 PM
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Re: A/C Clutch Cycle Switch Location?

Ahh, at least I know I'm not going crazy now. So if I jumper 2 of the 3 wires, it'll cause the compressor to run full time while I recharge the system? Which two wires do I jumper together?
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Old 05-26-2010, 01:33 PM
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Re: A/C Clutch Cycle Switch Location?

hi there.
it's not as simple as that. the pressure tranducer is using a 5 volt supply, a signal and a ground, this is no go. if you want the compressor to run continiusly you can place a jumperwire at the a/c clutch relay. it is mounted in the PDC (power distribution center) the location of the relay is discribed on the back of the cover.
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Old 05-26-2010, 05:27 PM
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Re: A/C Clutch Cycle Switch Location?

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Originally Posted by michael.wellejus View Post
hi there.
it's not as simple as that. the pressure tranducer is using a 5 volt supply, a signal and a ground, this is no go. if you want the compressor to run continiusly you can place a jumperwire at the a/c clutch relay. it is mounted in the PDC (power distribution center) the location of the relay is discribed on the back of the cover.
best regards
michael
Yeah, thanks man. I just got ahold of my buddy who has access to alldatapro and found that out. The sensor has 3 wires connected to it, 5V, Ground, and Sensor Output. In order for the compressor to run, the sensor output must be between 0.7V-4.56V. If it's under or over that reading, it won't work. A new sensor is $70.

Looks like I'll be jumpering the relay and determining if I have a bad sensor. Repped for your help.
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Old 05-27-2010, 04:07 PM
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Re: A/C Clutch Cycle Switch Location?

New idea for this weekend. I'm going to hook a AA battery up between the ground and sensor pins. The 1.5V should be enough to kick the compressor on, read the pressure, and let me determine if it's a bad sensor or not.
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Old 06-02-2010, 02:51 PM
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Re: A/C Clutch Cycle Switch Location?

sounds ok to me. let me know if it works. :-)
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Old 06-03-2010, 10:10 AM
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Re: A/C Clutch Cycle Switch Location?

I actually got this fixed yesterday and I'll go through that process incase someone uses the search function in the future.

I used the DMM leads to pierce the insulation on the pressure sensor. It read 1.3V. Anything between 0.7V-4.5V is good. So, this obviously wasn't my problem.

After thinking about it for a couple minutes, I decided start from electronics step one and properly check the fuse and relay. I pulled the relay and measured the resistance w/ and w/out power to make sure it was working (it was). Then I pulled the fuse to check it. Sure enough, it was blown. With a blown fuse, the compressor obviously wonít turn on.

So, I pulled the A/C wiring diagrams from the web and looked over them. I found that the A/C compressor clutch circuit goes 12V ŗ fuse ŗ relay ŗ C104 connector on firewall ŗ compressor clutch connector ŗ ground.

So I pulled the relay out and put the red lead of the DMM into the slot. As a sanity check, I placed the other lead on the negative of the battery and measured resistance. Sure enough, there was ~0 ohms. So I disconnected the compressor clutch and re-measured the resistance. Again, it was still ~0 ohms.

Then I disconnected the C104 connector on the firewall and determined which pin was the circuit I needed. As it turned out, itís pin 9. If I would have looked at the wiring diagram it told me for 4.0L LHD itís connector C104 Pin 9 (all others itís connector C102 Pin 12). I then measured the resistance from pin 9 to the relay socket. It was an open circuit.

So, the short was somewhere in the BIG wire loom that snakes through the engine. I started at the compressor side and inspected the wires as they came up from the compressor to the wire channel located next to the engine head. Everything looked fine so I regrettably move on.

I popped the top of the wire channel off. I noticed that where the wires come in at the end, the tape had been worn into. I put a rubber handled screw driver between the wires and wire channel (itís metal and grounded). I then measured the resistance between the connector and the battery and it was now open. I then installed a rubber grommet around those wires and everything works perfectly.

Now the question to the stupid Jeep engineers. Iíve always been taught when wires pass through any material, you need a grommet to keep the wear off the wires. Why isnít there any grommet in this location from the factory?
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Old 10-09-2013, 04:05 PM
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Re: A/C Clutch Cycle Switch Location?

I have a 2003 GC Overland edition and my air conditioner clutch does not disengage when I turn the ac off.
Any suggestions please.
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Old 10-09-2013, 04:23 PM
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Re: A/C Clutch Cycle Switch Location?

Quote:
Originally Posted by jonoroco View Post
I have a 2003 GC Overland edition and my air conditioner clutch does not disengage when I turn the ac off.
Any suggestions please.
Welcome to the garage.
First remove the compressor relay in the power distribution center and see if it will be off now. If not, the clutch is defective. If its off now, i have to see which wires to measure.
Update: Just thinking about this further, if you have selected defrost position for the air outlet, the compressor will be on all the time, independent on the state of the AC button light.
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Old 10-09-2013, 04:52 PM
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Re: A/C Clutch Cycle Switch Location?

Thank you very much for the info Frank. Even when I just select any other setting the AC still runs.
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Old 10-09-2013, 04:57 PM
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Re: A/C Clutch Cycle Switch Location?

So remove the compressor clutch relay in the PDC and check again. The relay could be stuck in on position. You could swap it with the horn relay and test again.
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