Re-wiring Napa Compressor

[psea17]

Hello, my peeps! Hope all of you are enjoying the summer!

Saw that a lot of people were rewiring their napa compressors and making a few changes to increase performance. So I followed along...the best I could. The diagram below is based on this video: https://www.youtube.com/watch?si=bihWU2nFc-9cvlrC&v=h2sGKHKqpNk&feature=youtu.be


This is what most suggest doing:

1. remove PCB board
2. replace PCB w/ a 200a relay.
3. widen the outlet to 1/4"
4. replace outlet connection w/ a standard air chuck
5. add a pressure switch
6. increase wire gauge to power source and replace w/ an Anderson Plug (AP)

I've done all of that. But I couldn't find the 200a relay and went w/ a 300a relay instead. Here's my problem. For some reason, neither the power switch or the air pressure switch are working. The compressor simply won't shut off unless I unplug it. I'm stumped.


I just replaced the air pressure switch and rather than using the cheap little switch that came w/ the compressor, I replaced it w/ a 30a switch of higher quality.

I can now air up 4 (32") tires at once from 12psi-40psi in 3 minutes. Happy w/ the performance. But I'm stumped as to why this isn't working. Clearly, I've done something wrong w/ the wiring, but I have no idea what's wrong.

I've attached my wiring diagram. Could the 300A relay be the cause?? I figured that would just give it more cushioning for power, but now I'm wondering.

Does anyone have any wiring suggestions? Here's the diagram. If wrong, I'll correct it and repost it. Perhaps it will help others in the future.

Thanks!!

 

[phattyduck]

Do you have more information on the relay? Pictures, diagrams, etc. There's definitely a wiring issue, just have to track it down.

I did a very similar mod to mine - and I was able to fit everything back under the stock covers with some work. So much faster to fill up tires!

-Charlie

 

[psea17]

Hey Charlie,

Other than the diagram above, all i have is links to what i bought.

relay. Amazon.com: Max 300A Continuous Duty Solenoid Relay Nickel-Plating for Winch, Golf Carts, Marine in Rush 12VDC E-Z-GO Gas Marathon Models with 2 or 4-Cycle Engines by Lucky Seven : Sports & Outdoors

pressure switches.
-1st one. Amazon.com: mankk Air Pressure Switch 70-100 PSI Thread 1/8" NPT 24V 12V DC Air Compressor Pressure Switch for Air Horn Train 70-100-1/8" NPT-BK : Automotive

-2nd one. Amazon.com: Air Pressure Switch 85-100 PSI 1/8"-27 NPT DC 24V 12V Air Compressor 100PSI DC : Automotive

new power switch. Amazon.com: Joinfworld Toggle Switch 12V DC 125V SPST 2 Pin Waterproof Marine Toggle Switch 12 Volt On Off Switch 30A Heavy Duty with Boot Cover for Automotive Boat Car Truck - 4Pack : Automotive


went back and found another video. looks like he connected the #3 wire labeled above to the pressure switch, not the power switch. going to give that a try i guess.

appreciate the response!

pc

 

[psea17]

2nd attempt. Different wiring based on this YT video. (https://www.youtube.com/watch?si=D4nSCSnbXOEAaxpn&v=1pZo4GWt4Q8&feature=youtu.be)

SAME problem. Neither the pressure switch or the power switch are keeping it off. It's as if they're not even there. I plug it into the truck and it runs. Stumped. Now that I've replaced the pressure switch and the power switch and rewired it, only other thing is the relay.

Here's the revised wiring:

 

[Ibrad]

The switch needs power. It doesn't matter where it gets its power from but what makes the switch work is being plumbed into the compressor tank so it can sense the 70-100 psi range that it's made to work in. If it is plumbed into the tank and it's not operating normally the switch may be bad. Cheapest solution to check would be if you have a real compressor to take its pressure switch and try it. If it works then your new switch is bad.

 

[psea17]

Thanks for the suggestion. I dont believe these compressors have tanks and im doubtful it's the switch or pressure switch as i just changed both. im hoping it's a failed relay. I'll know later today when the new one arrives.

head scratcher. kind of surprised no one else has made these mods and can share their wiring.

appreciate the help.

 

[Ibrad]

The pressure switch is designed to shut the motor off once the pressure reaches 100 psi and when the pressure dips below 70 psi it will kick the motor on so the pressure will not get below 70 psi. This pressure is held within a tank of some sort. If I understand correctly you have a compressor with a hose hooked directly to it with no tank for a reserve of air pressure?
If you hook the pressure inline with the hose that switch will work to start the motor once the psi is below 70 and will stop the motor once the psi is above 100. Unless I'm not thinking right the pressure switch is useless if you don't have a reserve tank of compressed air for it to regulate between 70 and 100. If at this point you can air up your tires in 3 minutes and manually toggle the pump off I'd say it's working and not worry about the fancy pressure switches. Just toggle your pump on, air up your tires then toggle your pump off and be done.

 

[psea17]

Ok, it sounds like you dont have much knowledge of these compressors. No tanks. Pressure immidiately builds if youre not dumping air into the tires.

These modifications did work as expected for a time. But then stopped working. Id turn it on and it would immediately cut out due to the pressure switch (and the fact i hadnt started airing up). Then, the moment i open the valve, air flows and the pump starts running again.

First, i thought the problem was a failed power switch (the switch that came w the compressor). Changed it. Didnt work whether the switch was in the off position or not. Then i replaced the air pressure switch. Same problem persisted. So i assumed it was bad wiring. Rewired it according to another video. Same problem.

So the only thing i havent swapped out is the relay.

Was hoping someone had already done these mods and could identify my mistakes.

Appreciate you trying.

 

[Ibrad]

Maybe someone with your setup will respond with the fix. Guess I'm thinking about any other 12 volt tire pump that runs all the time. Your new pressure switch could possibly be bad.

 

[psea17]

guess im confused why youre asking if it has a tank if youre so familiar w all these 12v pumps.

so just bad luck: both pressure switches bad plus both power switches bad? im not inclined to lean that way.

thanks

 

[phattyduck]

It really does sound like the next step is checking the relay.

Disconnect the wires and make sure there is no continuity between each of the big connections and any other connection. Make sure there is ~14ohms (it'll probably read 15 ohms or so) between the two small connections.

On the compressor, check which wires are directly connected. It should be the large and small reds together. Your wiring looks correct - interrupting power to the solenoid coil should disconnect the motor...

-Charlie

 

[phattyduck]

The pressure switch is designed to shut the motor off once the pressure reaches 100 psi and when the pressure dips below 70 psi it will kick the motor on so the pressure will not get below 70 psi. This pressure is held within a tank of some sort. If I understand correctly you have a compressor with a hose hooked directly to it with no tank for a reserve of air pressure?

The "tank" is the linking manifold between the two cylinders, along with any hoses connected. The pressure switch is there so you can dead-head the pump and it will turn itself off and back on automatically while filling tires (to check pressures, etc.) not keep a tank full.

-Charlie

 

[psea17]

Happy to report switching out the relay worked! I kept the wiring per the 2nd diagram.

HOPE it helps someone else and thanks to everyone who chimed in.

ps. just hit 300k mi. bought new in '98! friends have decided when i finally kick it, they're just digging a ramp, putting me in the truck, rolling it down and covering it up. lol