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Discussion Starter #1
So it’s getting really hot out there, and it’s fun to drive this little Neon.
But with no AC I’m sweating like crazy!

I pulled the AC clutch relay and installed a paper clip and the clutch activated.
I then charged the system with a can before I ran out. Kinda Cold air out the vents now. Definitely colder than before.

So I turned it off, put in the horn relay in place of the AC clutch relay, and the clutch won’t activate! Horn does work with that relay. What else should I check? Should I just buy another can to add more and get it in the green? Is the charge still to low?
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Yes you Are on the right track add more refrigerant until it’s in the middle of the green. lol Quit using a paper clip your gonna mess Something up.
 

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Here is why it works, what you should do....


The system requires a certain pressure to be seen before it will allow the compressor to kick on. Notice what i have circled in red. These pressure switches must be activated before the PCM "A/C Switch Sense" module will receive the signal.
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When the PCM wants the compressor clutch to kick on, it sends power from the "A/C clutch relay control" through the relay between post 85 and 86.

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This signal passes through a coil in the relay and inductively switches power from going between 30 and 87a to now go between 30 and 87.

The paperclip you've installed is shown in green on both of these diagrams. It is bypassing the 86 to 85 coil all together (orange "X") forcing the clutch to activate even though the PCM doesn't want it to.

As mentioned above, and you probably already knew this, you need to add more refrigerant to the system. I'm confident it will work as intended once you get the level where it is supposed to be.
 

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Discussion Starter #4
I’m not running it like that lol. I was just doing some trouble shooting.

Thank you for that very detailed information.

I now determined it has a leak. Everything I charged it with yesterday is no longer present. I used the paper clip again and had the car running. Connected the can with gauge and it now reads zero.

There is a noticeable hissing coming from behind the radio area. I’ve never noticed this sound since the clutch would never kick on. But now that’s it’s on I can hear it clearly. I’m considering of charging with dye to find the leak. A local shop wants $80 to diagnose the issue. I’m sure they will claim I need a whole new system. Another shop tried selling me a new system before even looking at it!
 

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Keep me posted on what you find out. Mine also has a leak somewhere and won’t hold a charge. I haven’t even begun to try to find the leak since I almost never use A/C.... yes, even with living in Georgia.... haha. I’m a windows down kinda guy.
 

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Discussion Starter #6 (Edited)
I will update once I find results. Anyone know where the hi and low pressure switch is? Are they under the hood connected on the lines themselves? Or are they found in the dash somewhere? I want to test them.

Also is a hissing noise behind the dash normal?

Found this, looks like it’s leaking here. Is the plug under that the switch? And what is that piece called? Expansion valve? What is that block? Low pressure pipe and high goes to it.

Also found the rubber hose has two knicks on it near the compressor pulley.

This is all just visual inspection before the dye kit gets introduced.


I’m learning so bare with me lol
 

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Discussion Starter #7 (Edited)
Can someone please unscrew their high pressure valve cap just too see if they also have this instead of a schrader valve please. I bought a new expansion valve and schrader valve and cap to replace mine. But the high pressure doesn’t have a schrader valve? It’s more like a rubber sphere in there. Is this normal? Could it be leak seal built up in there?
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Discussion Starter #8
Lots of help here! Lol

I figured out it’s a whole piece that gets replaced on the high pressure side, not just the internal valve stem.
 

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sorry i was going to try to look at mine for you but didn't get home until after you posted saying you figured it out. Can you post pictures or more info on what you figured out?
 

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Discussion Starter #10 (Edited)
Fixed the leaks, vacuumed the system and it held. Charged with two cans and one can with 1oz. of oil.
However the compressor clutch still does not come on with it’s own signal without jumping the relay.

I replaced the low pressure sensor, dryer/receiver, liquid line, expansion valve, and schrader valves.

The low side schrader valve was broken in the liquid line so the whole line needed replacing.

Finding the liquid line was so hard online, price is crazy for a new one. I found a good deal.

The fuse is getting power, I switched the AC relay and still the same.

Next is figuring out how to test the high pressure switch....then last resort will be a new compressor before I have to have a “professional “ look at it unless there is something I’m missing.

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