SensingRebuild shelfUnplug and unscrew
Pressure switch
Also called air switch, washer pressure switch.
A diaphragm and a snap switch, used in washers to know the water level. Usually a hose port and one or more clicks at different heights. Not a transducer: it is a threshold.
If you are new to this category
A sensor reports a condition such as weight, light, temperature, or position. Many sensors do not switch fully on or off. A kitchen scale bar, for example, changes by thousandths of a volt. Keep the small board that read the sensor if you still have it.
Keep the connector. Write down the wire colors before you cut them. If you do not know which wire is which, the sensor is hard to reuse.
Red and black feed the sensor a steady few volts. Green and white are the tiny signal, measured between them, not from either one to ground. Pressing the bar changes that signal by millivolts. A normal meter on DC volts can show that it responds. Turning it into a number on a screen wants a small amplifier board, often an HX711.
| What to look for | Usual figure |
|---|---|
| Port | A small hose barb. The switch sees air trapped in a tube, not the water itself. |
| Points | One or several levels. Map them with a breath or a syringe, gently. |
Volts are electrical pressure, amps are how much current is flowing, and ohms are how hard the part resists that flow. A higher voltage than the part was built for is how salvage parts die on the bench. If a cell in the table says “read the stamp”, that stamp is the whole specification.
What people actually use it for
- A level alarm
- A clogged-filter detector
- Any on/off pressure trip in its range
Leave this one when
The diaphragm is torn. It will never hold a level.
Buying a new one is the better idea when
A switch with a written trip pressure, if the trip point matters.
How to tell if this one still works
Beep the contacts while you apply a small pressure. Note which contact is which.
Tools you will want: Meter, A short hose.
Words on this page
Short meanings, so the rest of the entry is readable if you are not already doing this every weekend.
- diaphragm
- A flexible disc that moves with pressure or with a pump. In a washer it is how a small switch senses water level without the switch getting wet.
Where people actually find it
1 notes, most useful first. “Leave it” means the part is in that machine and you should not take it: it is dangerous, worn out, or only useful if you already know that exact repair.
| From | Call | How many | How often | Where it sits |
|---|---|---|---|---|
| Washing machine | Worth it | 1 | usually | On a small hose from the tub. |
- In this particular machine
- Air switch, one or more levels.
- Where to look
- On a small hose from the tub.
- How to get it out
- Do not lose the hose barb.
- The condition to expect
- Diaphragms get brittle.