Oba ??

bshaw · Jun 10, 2005

Hey guys got a few questions, and hopefully someone will know the answer. I'm hooking up my dealayed project (year now) for OBA. I do not want to hook everything up and have something blow up in my face. So this is what I'm wondering about:

I bought a compressor switch (would hook up to an actual garage comprssor), which takes a 120 v to run it. 1. Will my battery be able to keep up with this, or is it to much?

On the compressor switch, there are four power hook ups. Two say LINE on either side, and MOTOR on either side. 2. Would LINE mean battery hook-up, and MOTOR would run to the old a/c compressor?

3. How much psi will the old a/c comprssor with stand?

dmillion · Jun 10, 2005

To use that switch you will have to get an inverter, which will convert the 12v dc of your battery into 120v ac that the switch wants. Frankly, I think it would be cheaper and a whole lot easier to get a switch that's actually made for 12v automotive use.

Goatman · Jun 10, 2005

A 12v pressure switch from Sun Performance is cheap, and I'm sure you can get them other places as well. Sun Performance sells the QuickAir line of compressors, and they sell all the accesories that are used to hook them up.

bbaker80 · Jun 10, 2005

On and off aren't any different with 12V than 120V or 240V. Current is either passing through the switch or it isn't. The circut is completed when the air pressure decreases to a point where a mechanical switch activates the circut. That action is not dependent on voltage or amperage, it depends soley on the air pressure in the system. My OBA has been working fine (both a Quick Air 2 and my new A/C compressor setups) for a couple years now with a switch designed for 120V.

Now for your questions:
1. Your battery is just powering the compressor clutch, same as it did when you used to sit in traffic with the A/C on.
2. Line is in, Motor is out, you are correct.
3. My current setup cuts in @ 105psi and shuts off @125-135psi, depending on which guage you're looking at. I have a saftey valve under the hood set @150psi, and hopefully I'll never get to use it except to manually release the pressure when I park for the day, since I haven't gotten around to replacing the Wal-Mart air lines with something that dosen't swell and blow off in the middle of the night scaring the poo out of everyone in camp:speepin: :explosion :twak: . That being said, I can't tell you what the compressor's max psi is, but I'm sure it's pretty high.

bshaw · Jun 10, 2005

People posting quicker than I can post back lol.

bbaker80 said:
On and off aren't any different with 12V than 120V or 240V. Current is either passing through the switch or it isn't. The circut is completed when the air pressure decreases to a point where a mechanical switch activates the circut. That action is not dependent on voltage or amperage, it depends soley on the air pressure in the system. My OBA has been working fine (both a Quick Air 2 and my new A/C compressor setups) for a couple years now with a switch designed for 120V.

Now for your questions:
1. Your battery is just powering the compressor clutch, same as it did when you used to sit in traffic with the A/C on.
2. Line is in, Motor is out, you are correct.
3. My current setup cuts in @ 105psi and shuts off @125-135psi, depending on which guage you're looking at. I have a saftey valve under the hood set @150psi, and hopefully I'll never get to use it except to manually release the pressure when I park for the day, since I haven't gotten around to replacing the Wal-Mart air lines with something that dosen't swell and blow off in the middle of the night scaring the poo out of everyone in camp:speepin: :explosion :twak: . That being said, I can't tell you what the compressor's max psi is, but I'm sure it's pretty high.

Okay cool then. I have a regulator with a guage on it to set the psi coming out, plus a saftey pop up valve. Thanks to all you guys for the info. Really appericate it!! :cheers:

Roxtar · Jun 10, 2005

You didn't specify what kind of system you're using. If it's an AC compressor then bbaker is right, the switch just runs the clutch.
However, if it's a 12V compressor then the switch starts the compressor itself.
You also have to run a HD (50 amp or so) main on/off relay before the pressure switch if it's a 12V compressor.
You can get by with just a switch if its an AC system.
BTW, you're correct on the pressure switch wiring.

bshaw · Jun 10, 2005

kid4lyf said:
You didn't specify what kind of system you're using. If it's an AC compressor then bbaker is right, the switch just runs the clutch.
However, if it's a 12V compressor then the switch starts the compressor itself.
You also have to run a HD (50 amp or so) main on/off relay before the pressure switch if it's a 12V compressor.
You can get by with just a switch if its an AC system.
BTW, you're correct on the pressure switch wiring.

Yep it was a old A/C compressor I was using. I got everything hooked up and it is working well. My only problem is that my fitting (output) is leaking air, so now I'm going to have to get another one to fit better. I can not believe how fast these things build up air, 140+ psi in about 3 seconds. I can still air up my tires, but the fitting is going to have to be changed. While airing up my tire, the compressor is still generating 60psi. One more thing, the compressor still had oil in it. That's no biggy is it, I mean safe right?

Dirk Pitt · Jun 10, 2005

bshaw said:
Yep it was a old A/C compressor I was using. I got everything hooked up and it is working well. My only problem is that my fitting (output) is leaking air, so now I'm going to have to get another one to fit better. I can not believe how fast these things build up air, 140+ psi in about 3 seconds. I can still air up my tires, but the fitting is going to have to be changed. While airing up my tire, the compressor is still generating 60psi. One more thing, the compressor still had oil in it. That's no biggy is it, I mean safe right?

It has to have oil in it.

You have an oiler on the inlet side right? It will seize up if not.

Also wise to have a oil separator on the output side.

HTH

Rev Den · Jun 10, 2005

What type of comp?

Rev

Geepfreak · Jun 10, 2005

Dirk Pitt said:
It has to have oil in it.

You have an oiler on the inlet side right? It will seize up if not.

Also wise to have a oil separator on the output side.

HTH

I run the same set-up, and you really need a seperator, I have just run a line from the seperator to the inlet, with a small air filter ahead of that, just to keep things clean.

oh,,, I run 150# switch, with a 2.5 gallon home built air tank.

bj-666 · Jun 11, 2005

use a good quality hose coming off the compressor any cheepy hose will get hot and expand and blow i went thru about 3 before i got a good one. also move your filter away from the compressor the plastic bowl on most filters will melt and blow off as well

bbaker80 · Jun 11, 2005

bj-666 said:
use a good quality hose coming off the compressor any cheepy hose will get hot and expand and blow i went thru about 3 before i got a good one. also move your filter away from the compressor the plastic bowl on most filters will melt and blow off as well

x eleventybillion.

I did leave out hooking up a relay if you're running an electric comp, but question #3 was how much pressure can the A/C comp withstand, so I assumed the poster was running it, rather than an electric comp.

Don't forget, you will become VERY popular with those who do not have OBA so unless you want your air hose to become entangled in a plethora of waiting vehicles keep it under wraps until you absolutely need it. Good Luck.

bshaw · Jun 12, 2005

Dirk Pitt said:
Also wise to have a oil separator on the output side.
HTH

Yep, I have one away form the engine, next to the fender.

bj-666 said:
use a good quality hose coming off the compressor any cheepy hose will get hot and expand and blow i went thru about 3 before i got a good one.

I found this out yesterday after our trail ride. The hose and clamp on the output side kept blowing off, twice. Finally I tighten the damn thing down to the point of where it was almost cutting into the hose. After that the hose gave way and and the comp. blew a hole in it

.

bshaw · Jun 12, 2005

I'm heading to Lowe's today to see what I can fine. I need a new fitting for the compressor on the output line, it's leaking air. Plus I need to find some high pressure, high heat hosing. Does anyone have any suggestions on what to get as far as hosing goes? Also, there has got to be a way around using clamps, the system is putting out way to much pressure for any clamp to hold, just my opinion. A metal line would be awesome, or just a short peace of hose that has good fittings on both ends.

Something I was also wondering about is since I have the PSI gauge with an adjustor on it, will the compressor shut off on its own once the guage hits the set PSI. Or do I need something else to make the compressor stop pumping air? Since the air is leaking at the output fitting, I'm not for sure if the compressor will shut off or not.

Tried to draw a picture of what my set up looks like for anyone interested.

Rev Den · Jun 12, 2005

The system pressure at the switch will turn the compressor off. I used clamps on mine and have no problems at 110 PSI, clamps will hold, just use good hose, good clamps, barbed fittings.

Rev

RCP Phx · Jun 12, 2005

The pressure regulator should be after the pressure switch.Also, you dont show a separator/oiler in your drawing?
http://www.kilbyenterprises.com/accessories.htm

Gil BullyKatz · Jun 12, 2005

Rev Den said:
The system pressure at the switch will turn the compressor off. I used clamps on mine and have no problems at 110 PSI, clamps will hold, just use good hose, good clamps, barbed fittings.

Rev

I'll vouch for Rev's setup...

SWEET!

Ran the air tools without a whimper...

made an axle swap a walk in the park!

bshaw · Jun 12, 2005

Rev Den said:
The system pressure at the switch will turn the compressor off. I used clamps on mine and have no problems at 110 PSI, clamps will hold, just use good hose, good clamps, barbed fittings.

Rev

Well I guess I'm going to have to do this really.
I'm having problems finding a 3/4" NPT fitting for the out line on the compressor. I would like to do this for the out put line,

but I can find the parts. On the other hand, Kelby looks like they got some good hosing and fittings that will with stand the psi and temp, just not the 3/4" fitting I need. Thanks for the link BTW RCP.

Rev Den · Jun 12, 2005

Call Kilby and let them tell you and sell you what you need. 1 call does it all.

Rev

bbaker80 · Jun 12, 2005

Mine isn't as pretty as all that brass, but if you cut the metal line coming off the compressor from the factory a 1/2" compression fitting does the job just as well. From the compression fitting I used a Goodyear hose whip, with the swivel end. I figured the swivel would allow more engine movement without leaks, and the hose has factory crimped fittings. Since that hose gets a whole lot hotter than the rest of them, I figured that was the best connection available.

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