Air Compressor Pressure Switch Wiring Guide 2021

Pressure switch wiring is a smooth task unless you’re a professional. Because pros have experience. They know different working parts by their very definitions.

And of course, they know how these parts work. But as for beginners, they try to fix their air compressor without knowing the basics. And finally, end up with a dead weight.

In this guide, I am going to show you how to wire a pressure switch on an air compressor with step-by-step instructions.

Safety tips and warnings about different situations. So, at the end of this guide, you are ready to fix your pressure switch without any confusion in your mind.

There is a whole bunch of problems related alone to the pressure switch. I’ll also be discussing them in my future posts. But for now, we’ll stick to the scenario at hand.

So, here we are before we move towards wiring I’ll point out the list of items you need for the pressure switch wiring.

Items You Need For Pressure Switch Wiring

Air Compressor Pressure Switch

Choose the best-rated pressure switch for your air compressor. Also, confirm if it’s compatible with your air compressor.

Wire Strippers

If the wires are not stripped. You have to strip them yourself. Well, I usually remove 1 inch of the insulation of the wire. You can do according to your need.

Solderless Ring Terminals

They work as a hook anchor system on switch terminals. They are needed when you want to replace the old pair of solderings.

Screw Driver

The one you’ll need the most for tightening and loosening up the terminal screws.

Safety Gloves

Adds an extra layer of protection against electric shocks as well as scratches from rough, edgy areas.

A Good Conditioned Air Compressor

And of course the best air compressor from a trusted company. Sometimes, the pressure switch is fine. While your compressor has quality issues. So, also verify your compressor performance and behavior.

How To Wire A Pressure Switch on Air Compressor

Pressure-Switch-Wiring

Below are general instructions that apply to all types of air compressor pressure switches.

Time Needed To Complete This Project 30 minutes

1. List of Tools You Need For Wiring

1. Screw Driver
2. Safety Gloves
3. Wire Strippers
4. Solderless Ring Terminals
5. Compatible Pressure Switch
6. A Good Conditioned Air Compressor

2. Double-Check The Power Source

Now, you must double-check the power source. Remove or unplug the main electrical cord to avoid any electrical shock incident. Because when you are going to start wiring you have to remove the top cover of the box and the wires and terminals will be exposed.

3. Wear Safety Gloves

Well, what I would recommend is to wear safety gloves as an extra layer for protection. Sometimes, you are saved from electricity but scratches are the tiny things that will get you. And I have to deal with these situations a lot. I hope I don’t need to explain that.

4. Check Contacts/Terminals

Check the set of four contacts/Terminals. One set of the terminal will be for “Line/Power Cord” and the other will be for “Motor Cord”. The wires from Line and motor go into these terminals.

5. Check Terminal Markings

Look for markings on terminals. The companies always put labels on these types of areas so it won’t confuse the regular folks. There is a label on each terminal for line and motor cords.

6. Now, Check The Cord Color

The cords are obviously colored. Black, White, and Green. The only important thing is that the Black and white motor wire should go to motor-specific terminals. It doesn’t matter that you put the white wire into black’s place or black wire into white’s place. That’s it.

7. Attach Right Cord To Right Terminal

Did you remember, earlier I told you that for each pressure switch the terminal arrangement is different? You can check that mention in Air Compressor Pressure Switch Parts > Terminals.

8. Stripping The Wires

In some cords, the solderings are already attached with stripped wires. You just need to attach it to the terminals. But, if power and motor cords are not stripped, you should strip them by using a stripper. It will reveal the copper wires. Now, attach the solderings with these copper wires.
Advice: Well, if you ask me I only strip one inch of insulated wires in these types of cases.

9. Double-Check The Markings

Look at the markings and then loosen the screws with a screwdriver. Attach the motor cords with motor terminals and line/power cords with the line terminals.

10. The Green Wire & Screw

The green wire goes to the green screw on the metal frame of the pressure switch.

11. Start The Compressor

Put the cover over the switch. Start the compressor from the main power source.

A Video For Condor, Furnas & Square D Pressure Switch Wiring

Here is a video on how to wire different pressure switches. In this video, the three popular types of pressure switches are used. The Condor, Furnace (Hubbell), and finally, the Square D Pressure Switch.

A Video For Condor, Furnas & Square D Pressure Switch Wiring

How To Adjust Pressure Switch

As far as I am concerned with pressure switch adjustment. We can divide them into two types.

Adjustable Pressure Switch

The adjustable pressure switch has an adjustable screw present on it. With which you can adjust the cut-in cut-out pressure, and set the pressure differential. Such as Condor MDR-2 and Square D Pressure Switch. 

In the Condor MDR-2 model, there are two large screws with large springs. Rotate these springs to the clockwise manner and you can increase the cut-in pressure. And if you want to decrease the cut-in pressure then rotate them to the anti-clockwise manner.

Non Adjustable Pressure Switch

These pressure switch types are factory preset. You cannot adjust them because the adjustment screw is not present on them. In some cases, there is a silicone seal on it by the respective company.

These types of pressure switches are auto cut-in and cut-out at a preset pressure. Such as the Furnas Pressure Switch.

How To Adjust Pressure Switch

Here is another epic video on how to adjust your pressure switch. In this case, we’re going to use a Square D Pressure Switch Type.

Square D Pressure Switch Adjustment

Pressure Switch Wiring Safety Tips

In Instructions Section I already talked with you about the safety tips. Before taking any action, you should know the safety tips and warnings.

I know your work is important. But your health and life are more important than the work itself. What’s the point of that work when you are going to get hurt at the end of the day. Thus, you’ll be in no shape to perform other crucial tasks of your life.

Power Source

Whenever you are going to wire, adjust, or replace the air compressor. First cut the electric supply as it is a rule of thumb. Before you do any circuit work also turn off the air compressor from its switch. So, you can avoid electric shock or life-threatening incidents.

Protective Wears

My advice to you is to always wear safety gloves that are shock and scratch-resistant. Sometimes electricity doesn’t get you. But, anything sharp or with a harsh surface can cause scratches to your hands while wiring and adjusting.

Performance

I would also recommend you to check the health of your equipment. If the equipment is in a bad shape and is not able to work with the flow then don’t continue to use it. Faulty equipment is more dangerous in my book.

Wiring

When wiring you should be cautious. Check the wire colors and terminal labels before connecting the terminals with the respective cord. A wrong connection might cause a major malfunction or short-circuit.

Insulation

Now, this one is very important. Before start wiring or adjusting your switch, check the cords i.e., motor, power, and other circuit contacts for proper insulation. Sometimes the insulation gets damaged or get melted due to excessive electricity passage.

Pressure Switch Wiring Warnings

Here are warnings you need to beware of to avoid any mishap and damage.

Compatibility

Always, keep in mind the compatibility of the pressure switch with your air compressor. If you use a switch that is not up to the specified requirements of your air compressor then don’t use it. Check the specifications manual with the product.

Capacity

Don not burden the device with excessive voltage and load more than its capacity. If you do, the switch is going to get burned. Or in another case scenario, the switch is not burned but its lifespan will be shortened.

Quality

Another important factor is the quality of the pressure switch. Don’t put your hand on the top of the shelf brand with sparkles.

My advice to you is to look for high-quality products with the best ratings and reviews. The brand is not going to give you anything unless the product is up to the challenges.

Leakages

Another issue I have seen a lot is the leakage problem. So, check the pipes and the compressor tank carefully for any leakages before making any judgment. And if there is any leakage then fix them.

Seek Professional Help

Lastly, I would recommend you to call the professionals in your area or contact the company for issues that are beyond your expertise. If you are not able to do it yourself then leave the work to the pros.

Trying to do it yourself only cause you hundreds of dollars worth of loss. It’s better to spend a few dollars and get a professional rather than losing hundreds of dollars of air compressors.

Compressor Pressure Switch Wiring FAQs

Q: How to test a pressure switch?

Ans: Below are simple steps to test a pressure switch:
1. First, disconnect the wires by pulling the wire connectors from switch terminals.
2. Setup a multimeter to check and test for resistance (Ohms).
3. Touch the pressure switch terminals with each tester probe.
4. The multimeter will show 0 or close to 0 which indicates no resistance.
5. But, if the reading is higher then the pressure switch is busted up.
6. You have to replace or repair the air compressor pressure switch.

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