need help understanding relays for a project - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > General Jeep Discussions > Communications and Electronics

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 12-04-2011, 07:44 AM   #1
Jeeper
 
Kevbz's Avatar
 
Join Date: Apr 2011
Location: O'Fallon, MO
Posts: 1,637
need help understanding relays for a project

One of the longest builds I have ever done is my On Board Air system. I guess since I am keeping it cheap and waiting for the pieces I need to become available cheap!

Finally got the compressor, its a stock Chrysler a/c compressor. Now my jeep didn't have factory a/c so i am not going to use any of their wiring, because the relays are not there in the power distribution center, the factory plug dangling on my harness is different from the compressor I have, and my in cab switches are none existent since its not a factory set up. Also i dont want to have to worry about high side and low side pressure since at times my system will be empty, trying to KISS!

So I'm "custom" wiring up the clutch on this compressor. I've looked at the wiring diagram and from the a/c clutch I have ground and power, power comes from the a/c clutch relay, but only "passes through" it to the fuse panel, since i dont need any of the high/low side stuff can i wire it like this:

Looking at the diagram if I run a hot wire through a pressure switch like this one

(120 PSI 12V Pressure Switch for Viair Air compressor | eBay)

to control the power to the compressor, basically becoming my high/low shut off. then to a rocker switch in the cab to add user controll, and on to 10A fused hot lead from the fuse panel.

Am I good? I don't understand relays enough to know if i need to keep the compressor clutch on a relay. All i can see from the diagram is it gets hot all the time and hot on run brought into it and then ??? how it works from there I dont know!

Kevbz is offline   Quote Quick Reply
Old 12-04-2011, 03:53 PM   #2
Jeeper
 
Jma20a's Avatar
 
Join Date: Apr 2007
Location: Fairfield, CT
Posts: 3,046
It would be less troublesome if you went with an electric compressor for your on board air system

__________________
Dear Algebra, Please stop asking us to find your X. She's never coming back and don't ask Y.
Jma20a is offline   Quote Quick Reply
Old 12-04-2011, 05:54 PM   #3
Jeeper
 
Kevbz's Avatar
 
Join Date: Apr 2011
Location: O'Fallon, MO
Posts: 1,637
there's no fun in buying something and bolting it in. I enjoy the fabrication part of it and trying to make it look like a factory option.
Kevbz is offline   Quote Quick Reply
Old 12-04-2011, 07:23 PM   #4
Jeeper
 
Join Date: Sep 2011
Location: Rockingham, NC
Posts: 114
Quote:
Originally Posted by Kevbz View Post
One of the longest builds I have ever done is my On Board Air system. I guess since I am keeping it cheap and waiting for the pieces I need to become available cheap!

Finally got the compressor, its a stock Chrysler a/c compressor. Now my jeep didn't have factory a/c so i am not going to use any of their wiring, because the relays are not there in the power distribution center, the factory plug dangling on my harness is different from the compressor I have, and my in cab switches are none existent since its not a factory set up. Also i dont want to have to worry about high side and low side pressure since at times my system will be empty, trying to KISS!

So I'm "custom" wiring up the clutch on this compressor. I've looked at the wiring diagram and from the a/c clutch I have ground and power, power comes from the a/c clutch relay, but only "passes through" it to the fuse panel, since i dont need any of the high/low side stuff can i wire it like this:

Looking at the diagram if I run a hot wire through a pressure switch like this one

(120 PSI 12V Pressure Switch for Viair Air compressor | eBay)

to control the power to the compressor, basically becoming my high/low shut off. then to a rocker switch in the cab to add user controll, and on to 10A fused hot lead from the fuse panel.

Am I good? I don't understand relays enough to know if i need to keep the compressor clutch on a relay. All i can see from the diagram is it gets hot all the time and hot on run brought into it and then ??? how it works from there I dont know!

I would run a hot wire to the compressor and use the pressure switch you have linked as a ground side switch, and if you want to run an in-cab override, do so as a ground control switch.

I would run the ground control through a relay too, in order to reduce the amperage trying to run through a pressure switch.

Relays are really simple and if you wire the compressor with a constant fused hot, and controlled the ground side.

Assuming a standard 5 prong relay with 85,86,87, 87a and 30 terminals

85 - Power (could be tee'd off of the hot going to the compressor clutch)
86 - Ground - This would be the controlled ground coming from the pressure switch in the system. Just run one wire from a ground to the switch and the other side to the 86 terminal on the relay. If you want to be able to completely control the compressor from inside the cab run a three position toggle (center off, up on, and down for override (higher pressure than pressure switch allows)..

87 - Ground - This would be the wire running to the ground side terminal of the compressor

30 - Ground- Run a ground wire from the battery or other suitable ground to this terminal of the relay

87a - Not used...

A four prong relay could also be used, just used this as these are the most common.


If you need any help with the wiring, just shoot me a pm and maybe we can come up with a diagram for the way you want it done.
felix225 is offline   Quote Quick Reply
Old 12-04-2011, 07:38 PM   #5
Jeeper
 
Jma20a's Avatar
 
Join Date: Apr 2007
Location: Fairfield, CT
Posts: 3,046
Didn't know it was a under hood setup. Take pics along the way and do a wright up on it.

What are you doing for an intake?
__________________
Dear Algebra, Please stop asking us to find your X. She's never coming back and don't ask Y.
Jma20a is offline   Quote Quick Reply
Old 12-05-2011, 12:16 AM   #6
Jeeper
 
Kevbz's Avatar
 
Join Date: Apr 2011
Location: O'Fallon, MO
Posts: 1,637
Quote:
Originally Posted by felix225 View Post
I would run a hot wire to the compressor and use the pressure switch you have linked as a ground side switch, and if you want to run an in-cab override, do so as a ground control switch.........
that makes sense, controlling the ground side. I never really though about it that way, always just assumed everything on the hot side. Thanks for the ideas.

I am going to work on the plumbing thats still left and get the supplies for the electrical soon. My goal is to be done by an annual spring mud run so I can air down and up at my leisure and keep my air mattress pumped up!
Kevbz is offline   Quote Quick Reply
Old 12-05-2011, 12:33 AM   #7
Jeeper
 
Kevbz's Avatar
 
Join Date: Apr 2011
Location: O'Fallon, MO
Posts: 1,637
Quote:
Originally Posted by Jma20a View Post
Didn't know it was a under hood setup. Take pics along the way and do a wright up on it.

What are you doing for an intake?
I've already machined a plate with 1/4 npt to mount on the compressor to replace the stock lines.

I am debating on going in underneath the motors air intake (plastic stock type) and plastic welding a hose barb there, so my motors air filter does the filtering, and then just an inline oil mister before the suction side of the compressor.

or

mounting a bigger oiler on the firewall and using an k & n filter like the one pictured mounted on a custom bracket somewhere in the fender area.

or a combination of the two!
Kevbz is offline   Quote Quick Reply
Old 12-05-2011, 05:04 AM   #8
Jeeper
 
Join Date: Sep 2011
Location: Rockingham, NC
Posts: 114
The last time I looked into doing an EDC, I researched the oiler issue and the inline mister looks to be a good solution. From what I understand the larger inline oiler (silver/black one)require pressurized air in order to oil, to keep air driven piston pumps, tools etc oiled while working. I could be wrong, but thats what I am under the impression of.
felix225 is offline   Quote Quick Reply
Old 12-05-2011, 07:01 AM   #9
Jeeper
 
Kevbz's Avatar
 
Join Date: Apr 2011
Location: O'Fallon, MO
Posts: 1,637
Quote:
Originally Posted by felix225 View Post
The last time I looked into doing an EDC, I researched the oiler issue and the inline mister looks to be a good solution. From what I understand the larger inline oiler (silver/black one)require pressurized air in order to oil, to keep air driven piston pumps, tools etc oiled while working. I could be wrong, but thats what I am under the impression of.
hummm...another thought I didn't think of, and that makes sense also.

That's why I love forums!
Kevbz is offline   Quote Quick Reply
Old 12-05-2011, 11:35 AM   #10
Jeeper
 
Jma20a's Avatar
 
Join Date: Apr 2007
Location: Fairfield, CT
Posts: 3,046
Yes those oilers are for compressed air. I use the larger ones at work for the compressed air system we have. We have tried to use the smaller one for on site portable compressors but doesn't work well.
__________________
Dear Algebra, Please stop asking us to find your X. She's never coming back and don't ask Y.
Jma20a is offline   Quote Quick Reply
Old 12-05-2011, 11:38 AM   #11
Jeeper
 
Jma20a's Avatar
 
Join Date: Apr 2007
Location: Fairfield, CT
Posts: 3,046
You should also look into an air filter for the output to keep any condensation out of the system.
__________________
Dear Algebra, Please stop asking us to find your X. She's never coming back and don't ask Y.
Jma20a is offline   Quote Quick Reply
Old 01-12-2012, 04:02 PM   #12
Jeeper
 
Kevbz's Avatar
 
Join Date: Apr 2011
Location: O'Fallon, MO
Posts: 1,637
been a while but I got some time to mess around today. I have the relay wired with long pigtails ready to hook up

I drew a diagram on how I thought it was described as a ground control relay. I am curious if my cab switch is in the right spot. Once I get sorted on this I should be good to go, the plumbing is done and it holds air nice, time to bring it alive!
Kevbz is offline   Quote Quick Reply
Old 01-12-2012, 06:15 PM   #13
Jeeper
 
Join Date: Sep 2011
Location: Rockingham, NC
Posts: 114
Everything looks like it is wired correctly depending on how you want the in cab control to work. The way it is drawn up, the switch will light anytime the compressor is on, and the switch will turn the compressor off regardless of the pressure switch..this is a good thing..What you won't be able to do is override the press switch to run a higher pressure.

Also, I would run the constant positive to the relay off of an ignition switch controlled power from the fuse box..so that if you were to forget to turn off the in cab switch, the compressor won't kick on at 2am and kill the battery..
felix225 is offline   Quote Quick Reply
Old 01-12-2012, 07:01 PM   #14
Jeeper
 
Kevbz's Avatar
 
Join Date: Apr 2011
Location: O'Fallon, MO
Posts: 1,637
Awesome, time to buy some fancy switches!

__________________
Per Mare, Per Terram...Semper Fidelis
Kevbz is offline   Quote Quick Reply
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Eagle Scout on the Rubicon... Great project!! Tread Lightly Land Use Forum 0 08-31-2011 04:11 PM
Where do you guys put your relays and fuses for your aftermarket parts at? Djstorm100 JK General Discussion Forum 24 06-20-2011 08:40 PM
1991 YJ Restoration and build up project begins SwatCop Builders Corner 21 01-10-2011 11:53 AM
ADVICE - May have found a project jeep Bryanherron General Jeep Discussion 11 08-23-2010 07:07 AM



» Featured Product

All times are GMT -5. The time now is 06:37 AM.



Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC