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A/C to OBA conversion write up -PICS

290K views 296 replies 109 participants last post by  dave564 
#1 · (Edited)
Ive really needed on board air for awhile now and i finally got around to doing it. I had three main options: An electric compressor, a belt driven compressor, or a C02/Nitrogen tank. I decided on a belt driven compressor for a few reasons. They put out way more CFM then an electric compressor, theyre quieter then an electric compressor, they have a 100% duty cycle, and if done right will probably be cheaper. I also seriously considered using a C02 tank, but one drawback to having a C02 tank is that it will obviously need to be refilled periodicaly, and with amount of air ill be using a C02 tank just wouldnt work best for me. As for what type of belt driven compressor i was going to run i had to decide between a York, or my stock A/C compressor. I dont use my A/C often and due to condensor issues it has never really worked properly. I figured this would be the easiest/cheapest route since the compressor was already installed, i just needed to do the plumbing. The stock Sanden compressor puts out about 8-9 CFM which is quite a bit, especially compared to the expensive electri compressors that only put out 1-2 CFM. The highest rated electric comp i could find is the Extreme Air compressor, which goes for about $380 and puts out 4 CFM at 0 psi. Anyway on to the install..

I started by removing all the A/C hoses and fittings. I then used some 3/4 to 3/8 pipe reducers on the input and output of the comp.


Then came the intake. The Sanden compressors are lubricated by the freon in the A/C system. With no freon you have to have an alternate way of lubricating the conpressor. The most common and efficent method is to use an inline air tool oiler, which is what i did.
Heres the intake, i used a valve cover breather fiter as an airfilter-

Oiler:

Now for the output. The output goes through a check valve, then through an air filter and seperator. The idea of this is to collect any condensation an oil that gets through the compressor. Not totally neccesery but its good to have. The line from there splits at a "T", one line goes to my front airline disconnect and the other goes to the rear of the jeep to the tank and manifold.

Under hood junk complete:

Next was to assemble the Manifold. I could have used the tank as a manifold since it has 6 ports on it but this manifold would keep thngs neater, more organized, and i wouldnt have to worry about braking a guage or somthing off the tank when putting tools and such in the back. I purchased the manifold for 12 dollars on www.northerntool.com
Here it is assembled.. saftey reliefe valve, pressure switch, and gauge.

I go the tank and pressure switch on ebay for an awsome deal. 50 bucks for both. The pressure switch is the Kilby switch, which turns on at 120psi and turns off at 150. Higher then neccesery but the price was right, and the only other small pressure switches i could find shutoff at 105. Id rather be high then low in this case. The tank is the Viair 2.5 gallon tank. I mounted the tank and manifold where the spare tire used to be which made for a clean look and didnt take up any useable space.
Tank and manifold mounted and lines run.

Now all i had to do was wire it up and i was good to go. I put a switch on the console which then runs to the pressure switch.
Switch:

All i do is flip the switch and the compressor kicks on until the system reaches 150psi, it turns off and wont kick on again ill it gets to 120. The system pressurizes very quick. From 0 to 150 psi takes just over a minute. I havent got an exact time but it filled my 33x12.50s from 9 to 32 psi in about a minute as well.

Front connect:

Rear connect:
 
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#2 · (Edited)
No useable space taken up by system:

At 150 psi and 8 CFM the system runs air tools just as good as my 12 gallon shop compressor.


All in all im real happy with the system, its probably one of the most useful mods ive made to date. Everything used can be bought at a local hardware store or home depot or lowes. Total cost was $125.
 
#5 ·
what an awsome write up!! for sure many people, including myself, will be attempting this.


thank you
 
#7 ·
Thanks for the comments...
For the electrical questions i simply disconnected the wire the magnetic clutch on the compressor. I ran 12 volts right from the battery through a 5amp inline fuse. The wire then goes to my switch on the console, that switch goes to the pressure switch, which goes to the comepressor clutch. So when i flip my switch it supplies 12 volts to the pressure switch. If pressure is below 120psi the pressure closes which engages the compressor and it automatically shuts off at 150 psi.
 
#10 ·
law.74 said:
Having mounted the tank on it's side how will you drain it, short of dismounting it?
I dont actually dismount the tank, bought i do take a few screws out of that panel to where i can just angle it to the drain **** which is on the end. Its pretty quick and easy. There was really no other good way to do it, i considered welding a bung in for a drain on the "bottom" but didnt feel like it and this works just fine.
 
#14 ·
Man that is a Great write up, I know what I am going to be doing with my AC pump. My Condenser went on me this summer. The would be a great mod for me as I autocross a car as well would be nice to be able to fill up tanks or use air tool at a race.]


should be a sticky
 
#15 ·
Doulbe post.

Can you get a parts list for all of us who want to do this mod?
 
#18 ·
Thanks guys.. as for parts, i may miss a couple things but here are the basics:

1.A/C compressor (obviously)
2.About 30 feet of 3/8th air hose
3.Air filter
4.Lots of 1/4 NPT to 3/8 hose barb fittings.
5.Inline air tool oiler
6.Check valve.
7.Air manifold
8.Saftey reliefe valve
9.Pressure switch
10.Tank
11.Oil recovery filter
12.Hose quick connects and other fittings
13. switch.
 
#205 ·
I read this whole thread, this is the best thread I have seen yet on JF, a HUGE round of applause for Russo! ! ! !

To make sure I have all this right, the check valve is what prevents the pressure from feeding back in to the compressor?

What is NPT stand for?

I noticed someone say they got a compressor made just for OBA that doesnt need an oiler, what kind of compressor was that and do you have a link to a supplier?

My TJ is the 2.5, and was never equipped with an a/c, but the mount is there, will I need just a longer serpentine belt or will I have to add another idler pulley as well?

Thank you for all the replies everyone has made, this has been the greatest example of Jeep guys helping each other out and no bickering, its awesome.
 
#20 ·
THIS SHOULD BE A STICKY!!!!

im really glad you did a writeup on this as this is EXACTLY what ive been looking for!
 
#22 ·
Nice writeup. I just completed my York OBA setup, so that I can retain my factory A/C. And I mounted my 2.5 gal Viair tank in the exact same spot as you.

There's a little more work involved, like re-routing the A/C lines, moving the battery to the other side, and spacing out the clutch fan to clear the York pulley.

Kilby's website has a lot of good info, such as diagrams and parts lists, that I used to piece my setup together.

www.kilbyenterprises.com
 
#23 ·
XJohnnyC said:
Nice writeup. I just completed my York OBA setup, so that I can retain my factory A/C. And I mounted my 2.5 gal Viair tank in the exact same spot as you.

There's a little more work involved, like re-routing the A/C lines, moving the battery to the other side, and spacing out the clutch fan to clear the York pulley.

Kilby's website has a lot of good info, such as diagrams and parts lists, that I used to piece my setup together.

www.kilbyenterprises.com
Yeah i considered the york, but this was cheaper and easier, since i already had the compressor mounted and, and i dont have much room for another compressor. The york is a great way to go though, espicially if you want to keep the A/C. Kilby does have a nice website and products, though there stuff i a bit pricey. Im real happy with their pressure switch though. :thumbsup:
 
#24 ·
Not to rain on anyone's parade or anything....

But I was talking about this thread to a mechanic buddy of mine. He says the Sanden is not a good compressor to use for OBA. He has seen people do this mod and have the compressor seize up on them. Something to do with the oiling system.

He has seen someone go through three Sandens, and they all seized up after a short period of time.

Hopefully, these are exceptions and not the rule. Let us know how your setup works out, RussoGuitar.
 
#26 ·
Ive been running the air system very hard lately and its been doing awsome. I couldnt be happier with it. The inline oiler seems to be doing its job because the recovery bottle filter has been collecting oil in it so i know the compressor is getting lubricated. Ill keep you guys updated though if any failures occur. And Ruffedup, just disconnect the wire going to the compressor clutch and run a small jumper wire from it to the battery. If the clutch engages then the clutch is good, youll here it click. YOu can do this with the engine running to make sure the comp isnt seized.
 
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