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Onboard air from stock AC compressor, pressure switch

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Onboard air from stock AC compressor, pressure switch

Old 03-27-2018, 06:11 AM
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Default Onboard air from stock AC compressor, pressure switch

What pressure switch are you guys using? Is there an over the counter option or am I going to have to bust out the msc catalog?
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Old 03-27-2018, 11:12 AM
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I use a 150# switch with a 200# relief valve. You are going to use one aren't you? That compressor will pump 400 psi easily. You can get them from various places. I got one from Amazon. Kilby Enterprises has all that stuff if you cannot find it anyplace else. Did you plumb in a check valve? You will need one of those too. Best not to try to start the compressor under load or have your pressure bleed back out through the compressor valves when it cycles off

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Old 03-27-2018, 11:17 AM
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Might want to figure out how to lube it or it won't last long. The internals of an AC compressor needs to be lubed or it will fry.
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Old 03-27-2018, 11:22 AM
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Originally Posted by Bugout4x4 View Post
Might want to figure out how to lube it or it won't last long. The internals of an AC compressor needs to be lubed or it will fry.
You can lube them internally if you vent the crank case. I have run the one in the vid for about ten years now internally lubed. If you don't vent the crank case, the internal pressure will push the oil out past the piston rings and run it dry
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Old 03-27-2018, 11:30 AM
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Originally Posted by 4.3L XJ View Post
You can lube them internally if you vent the crank case. I have run the one in the vid for about ten years now internally lubed. If you don't vent the crank case, the internal pressure will push the oil out past the piston rings and run it dry
Great job. It just needs some sort of lube. Once the closed system and lube charge is removed it needs something to replace that.

The old Chrysler V twin compressors were the best for making these. They actually had an oil pump in the crankcase that pressurized the crank and rod bearings. But they were big and needed lots of room. lol
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Old 03-27-2018, 12:16 PM
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That is the nice thing about an AC compressor, compact and lots of air
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Old 03-27-2018, 01:34 PM
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Originally Posted by 4.3L XJ View Post
I use a 150# switch with a 200# relief valve. You are going to use one aren't you? That compressor will pump 400 psi easily. You can get them from various places. I got one from Amazon. Kilby Enterprises has all that stuff if you cannot find it anyplace else. Did you plumb in a check valve? You will need one of those too. Best not to try to start the compressor under load or have your pressure bleed back out through the compressor valves when it cycles off

https://www.youtube.com/watch?v=q39yoOjlU4c
I haven't started plumbing it yet, never even crossed my mind to add in a check valve. I'll check the video out when I get home. The relief valve I'm just going to pull off an old air compressor I have laying around.

Originally Posted by Bugout4x4 View Post
Might want to figure out how to lube it or it won't last long. The internals of an AC compressor needs to be lubed or it will fry.
Since the compressor is lubed with oil circulating through the system, I've considered putting a "T" in my PCV line and pulling air in through that.
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Old 03-27-2018, 05:06 PM
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Originally Posted by skife View Post
Since the compressor is lubed with oil circulating through the system, I've considered putting a "T" in my PCV line and pulling air in through that.
Pulling oil mist from the crankcase you mean? I don't see why that wouldn't work. Wouldn't be much different than a two cycle engine lubrication system. Doesn't take much just has to have some.
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Old 03-27-2018, 05:47 PM
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Originally Posted by Bugout4x4 View Post
Pulling oil mist from the crankcase you mean? I don't see why that wouldn't work. Wouldn't be much different than a two cycle engine lubrication system. Doesn't take much just has to have some.
yeah, that's the idea, i figure the air leaves an oil residue in the air filter intake tube, hopefully that's enough to keep everything ok. if not, i'm in michigan, quite a few cherokee's headed to the junkyard every day.
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Old 03-27-2018, 06:32 PM
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Originally Posted by skife View Post
yeah, that's the idea, i figure the air leaves an oil residue in the air filter intake tube, hopefully that's enough to keep everything ok. if not, i'm in michigan, quite a few cherokee's headed to the junkyard every day.
Might work! I would be curious how it affects the engine vacuum. You may want to put a check valve there too so that when it is off it can't bleed back though as a vacuum leak. I wonder if it will end up being a vacuum pump? If you do this please let me know how it turns out and affects the engine vacuum?
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Old 03-28-2018, 05:53 AM
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Originally Posted by Bugout4x4 View Post
Might work! I would be curious how it affects the engine vacuum. You may want to put a check valve there too so that when it is off it can't bleed back though as a vacuum leak. I wonder if it will end up being a vacuum pump? If you do this please let me know how it turns out and affects the engine vacuum?

It shouldn't affect the engine vacuum at all as it's sucking air from the crank case, there is more than 1 vent in the valve cover and vacuum comes from the intake.
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