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2016 Pro-4X CC
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Discussion Starter · #1 ·
I got a deal on a compressor a few months ago and recently performed some mods on it to make it more suitable for my use. I figured it would be worth doing a write up so others could benefit. I primarily followed these two write ups, but felt there could be more photos of the wiring situation. I also wanted to try and give back to a forum that I spend a lot of time lurking and learning on. I should note that I'm by no means any sort of expert and the last time I played around with electricity I was 8. There's probably a better way to do everything here that I've done.
TacomaWorld
Baystate Jeepers

I purchased this compressor for $80 back in October. In reality it's just a re-branded Smittybilt 2781. I believe there are other re-badged versions of this compressor out there. A solid compressor for my needs (truck tires, bike tires, air mattress), but it has two glaring shortcomings:
  1. No auto-shut off. The lack of a pressure switch requires that the system be open constantly. You're be unable to use an air gun style attachment to fill up without constantly tripping the relief valve. The included screw-on chuck leaves a lot to be desired. This is remedied by wiring in a pressure switch.
  2. Nitto type fittings. These are non-standard and don't connect with NPT. Even after wiring in a pressure switch, easily findable fittings won't connect to the compressor.
Here are the parts I used for the pressure switch mod, broken up on by where I was able to find them. These are parts I used, if you think there's a better method, try it!
Amazon:
  1. Viair 90223 90/120 Pressure Switch
  2. 1/4" Male x 1/8" Female NPT Fitting
  3. 1/4" NPT Female X M12 x 1.25 M12X1.25 Male Metric Adapter
Home Depot/Lowes:
  1. 1/4 in. Female x 1/4 in. Female x 1/4 in. Male Brass Tee Fitting
  2. 1/4 in. x 1/4 in Male Coupling
  3. 1/4 in x 1/4 in Female Coupling
  4. Thread tape
  5. 14 ga. stranded wire
  6. Wire nuts
  7. NPT quick disconnect fittings
  8. Wire stripper
Tools I already had:
  1. Allen keys
  2. Screw driver
  3. Sockets
  4. Various wrenches
  5. Electrical tape
  6. Pocket knife
I started by disassembling the base, this required a screwdriver and a 10mm wrench.
324918


On the side of the compressor with the switch and the line exiting, With an Allen key I removed the lower metal bracket and the upper piece of flat metal which connects the handle to the body of the compressor. This upper piece is also sandwiched between the handle, a cap, and the exit hose. This requires a wrench.
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Once the hose and four bolts are removed, I could access the wires. Inside I could see the power cables, reset switch, power switch, and the relay. The reset switch can be removed by loosening the flat nut on the outside of the compartment. The relay can be removed by popping it out of its retaining clips.
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The relay is a Jd1912 12v 60a relay. Between this relay and the power switch, and next to a red wire, there is a black wire coming out of port 86, only a couple inches long. I cut this black wire based on my vague recollection of college courses and some on the spot googling/research. To each of the newly created ends I nutted (don't know the technical term) an 10ish inch length of 14 ga. wire.
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I'm skipping over the wiring install because I don't feel qualified to put any sort of advice out there, but once I had everything taped up tightly I installed a hole in the side of the canister on the same side as the blow off valve on the compressor. I then threaded both newly installed wires out of the hole, taped up to protect the wires against the edges of the hole.
I then re-installed the compartment, bottom bracket, and base, as well as the top pice of metal. I left the hose uninstalled.

On the exterior I uninstalled the pressure release valve. This has a female NPT inlet. I taped and threaded in the male - male and female - female NPT connectors in order to give the tee clearance past the vanes of the heat sink.
To the side of the tee furthest from the wiring I re-installed the relief valve, re-taping the threads. To the side nearest the wiring I taped and threaded in the 1/4" male - 1/8" female adapter, then threaded into that the pressure switch.
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Once everything was snugged up, I nutted (again, don't know the technical term) the wires included with the pressure switch to the wires I installed through the side of the switch canister. My understanding is that directions don't matter as it's a simple switch, and it hasn't exploded yet.
Once the switch was nutted, I taped the wires with electrical tape and zip-tied them to reduce the chance of catching. At some point I should get some sort of cover for these wires.

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The last step is to fasten the handle to the metal plate and cap via the 1/4" NPT Female X M12 x 1.25 M12X1.25 Male Metric Adapter. Into this I installed a 1./4" threaded NPT male quick disconnect fitting.
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The compressor can now be used with the attachments of your choice!
I can't verify the pressure ratings on the switch, but it turns the compressor off when I let go of the air gun's trigger, and it turns it back on again when I pull the trigger again. Both the relief valve and my hose are rated to 150 psi, so I'm somewhat confident both of those would fail before the compressor itself did.

Let me know if I built a ticking time bomb, or if you have a better way to do it!
 

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Nice job. Pretty silly that they don't come with a pressure switch since the duty cycle on that pump is so low.

The only thing I would change is to use butt connectors or insulated male/female spade connectors where you used wire nuts.
 

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2016 Pro-4X CC
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Discussion Starter · #3 ·
Nice job. Pretty silly that they don't come with a pressure switch since the duty cycle on that pump is so low.

The only thing I would change is to use butt connectors or insulated male/female spade connectors where you used wire nuts.
That's a good recommendation, I'll swap those in at some point in the future. I think it'd clean up some of the mess inside of the canister as well.
 
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