Pressure Switch 412024-E

Disconnect the compressor form the power source. Remove the old air filter by unscrewing it from the cylinder head, then screwing the new one in. Disconnect and remove the parts on the pressure switch that do not come with the new one. Take the cover of and remove the wiring, remembering where the wires go. Remove the old pressure switch. Attach the new switch. Open the cover and connect the wires. Close the cover. Connect all of the parts that were removed from the old switch to the new switch.

My 4-year-old, trouble-free Makita MAC5200 air compressor started leaking air from the off/on pressure switch, so I decided to fix it myself. It can't be that difficult, right? Well, what looked like an easy disconnect & unscrew of the switch turned out to be over an hour long (almost full) disassembly of the compressor but, as a former electrician and auto mechanic, I knew I could get it working.
I advise you to take clear pictures of the switch unit before you take it apart. The black and white wires in the power cord must be connected properly or there will be a big problem. AND make sure you DO NOT switch the "line" cord and the "motor" cord when you reconnect them onto the switch later. OK? Let's do this:
Check to see that the new switch is an exact replacement for the old one. Next, use a wrench to ensure that the little brass valve on the side of the switch is tight. Be careful not to bend its mounting bracket or it will cause an air leak and it's hard to get to it once the switch is reattached to the tank.
Disconnect all 6 wires of the 2 electrical cords from the old switch. You'll need a good pair of pliers to compress the power cord's "strain relief bushing grommet". Find the moveable side of it and squeeze it tightly then pull it out of the hole in the switch housing.
GENTLY unscrew and remove the U-shaped copper tubing nut from the side of the switch and the black plastic tubing nut from under the switch. Be careful not to kink or bend that copper tube.
At this point, I thought I could simply unscrew the old switch from the air tank but boy was I mistaken! I needed just 1/4 inch more of clearance from the motor and I could have removed the old switch easily. Instead, I had to turn the unit on its side and remove the 4 nuts that held the motor to the base to get it out of the way. Hoping it would give me the clearance I needed, it did not! The motor moved up a bit but STILL not out of the way enough.
I had to remove 2 small screws that were holding the upper plate to the frame. NOW I could move the motor up and out of the base to get that extra 1/4 inch that I needed. REALLY MAKITA! Finally, I was able to unscrew the old switch and remove it.
With a round wire brush, I cleaned the threads and the inside of the opening where the switch screwed onto the tank since there was some "crud" built up inside it. I put some Teflon tape on the threads for a tight seal. I screwed the new switch onto the threads and made sure it was tight and sitting perfectly vertical so the copper tubing will reattach properly.
BE VERY CAREFUL, when tightening the new switch, since there really isn't a good way to grasp it to tighten it. If you bend or damage the case or the little brass valve on the side, you will cause an air leak.
I reconnected the U-shaped copper tubing to the side of the switch. (There was no thread sealant on it from the factory, so I didn't use any). NOTE: Hand tighten the nut first making sure the flared end of the tubing is seated onto the brass valve properly or air will leak out. You will need 2 wrenches to tighten it. One to tighten the copper tubing nut and another to hold the small brass valve that it screws onto. BE CAREFUL not to damage or bend that little brass valve on the side of the switch or you will cause an air leak.
Now reconnect the black plastic tube under the switch. It has a small plastic, compression sleeve over the tube so be sure it's there and not damaged when you reattach it. (No Teflon tape needed there either).
Reattach the motor to the base with the 4 nuts and lock washers then reattach the top plate to the frame.
(You're almost done folks). If it came off the cord, reinstall the "strain relief bushing grommet" over the POWER cord exactly where it was before and carefully push it into the round hole in the side of the new switch housing. Look carefully at the 4 electrical screws on the new switch. There are 2 upper screws and 2 lower screws. The lower 2 are for the power cord (line) that you plug into the wall outlet and must be connected first. (It's very hard to see it but it says the word "line" on the black plastic). The upper 2 screws are for the "motor". cord. Again, make sure the black and white wires are connected to the proper screws.
Put the ground screw through the eyelets of the 2 green ground wires, screw them into the hole on the bottom of the switch case and closed the air release valve under the tank. Replace the switch cover.
I plugged it in and moved the switch lever down and the compressor filled itself up and made a good solid shutoff. What a good feeling! Best wishes folks!

Removed what was left of the existing cover and pressure switch. Replaced both.

Removed switch cover
Disconnected electric wires
Disconnected all air pressure fittings
Disconnected switch assembly from tank
Replaced fittings using teflon tape
Reconnected wires
Installed switch cover
Worked great.

1. Unplug it.
2. Took off both hoses.
3. Unplug bolted the compressor. Only 4 bolts. Pulled it out of the way.
4. Took a picture of the wiring. Unplug the wires.
5. Unscrewed the pressures switch.
6. Put pipe tape on the threads.
7. Installed new pressures switch.
8. Wired it up.
9. Put compressor back in place. Tighten the 4 bolts.
10. Hooked up the 2 air lines.
11. Plugged it in and turned it on.
12. Adjusted air pressures.
Works great

Makita compressor, had to remove a lot more items than should have been necessary to facilitate turning the switch.

Removed and replaced pressure switch, gauges and connectors.

1. I removed the damaged switch
2. removed two lines from old switch
3. removed one fitting off old one.
4. removed up cover that holds gauges.
5. removed bolts holding compressor pump and motor.
6. moved pump over to install the new pressure switch on the tank.
7. hook up lines and power wires to new switch.
8. move pump and motor back in place and bolt down cover.
9. test new pressure switch.

1. Disconnected power cord and switch leg
2. Removed plumbing connections
3. Removed regulator and plug from pressure switch
4. Removed old pressure switch from compressor tank
5. Installed regulator and plug to new pressure switch
6. Installed pressure switch to compressor tank nipple
7. Install power cord and switch leg to new pressure switch