Testing a Washing Machine Water Level Switch

Whirlpool Water level washing machine switch
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Your washing machine has some internal switches that control various functions, and any one of them may go bad and require replacement. A faulty water level or pressure switch is one that can prevent your washer from working properly if it goes bad. 

The Function of the Water-Level Switch

The water-level switch sends power from the timer control to the water inlet valve and the temperature switch each time the tub needs to be filled during a wash cycle.

The switch cuts off the water flow when the water level inside the tub correlates with the setting for a large, regular, or small load, and then signals the motor to begin agitating. The water level switch is found in different places on different machines—in many cases; it’s inside the control console.

You can distinguish the water-level switch from other round switches inside the washer cabinet by a rubber tube that runs from the switch down the side of the tub. As the washer fills, water enters the tube from the bottom and increases pressure in the airspace within the tube. When the pressure reaches the critical point, the switch shuts off water flow to the tub.

Before doing any inspection or work on your washing machine, make sure to unplug the electrical supply.

Inspecting the Tube

  1. Find and inspect the tube that leads from the bottom of the water-level switch to the bottom of the tub. It should be firmly connected to fittings at each end.
  1. Disconnect the tube from the fittings to which it’s attached at each end. This usually involves loosening clamps so that you can pull the tube off the fitting.

  2. Inspect the disconnected tube at each end for debris, sediment, and water.

  3. Inspect the tube for kinks and or holes—if you find any, that’s a problem that needs to be corrected by straightening or replacing the tube.

  1.  Clean and clear the tube if you find gunk in it. A good cleaning may be all that’s needed to correct a malfunctioning switch, but continue troubleshooting with the next step.

Testing the Switch

To test the switch for continuity, you'll use a multimeter (also called a volt-ohm meter) set at OHMS x 1.

  1. Find the wires leading to the terminals of the switch. Disconnect them from the terminals: this usually means disengaging a plug, but if the wires are connected to the terminals by other means, label them for position before disconnecting them.
  2. The water-level switch has three terminals. Test them for continuity in pairs. First, touch the meter probes to terminals 1 and 2.  Note the reading, which should be either ∞ infinity (infinity, which means no continuity) or some value close to 0.0 (continuity).
  3. Repeat the test touching the probes to terminals 1 and 3, and note the reading (∞ or approximately 0.0).
  4. Repeat the test touching the probes to terminals 2 and 3, and note the reading. 
  5. Analyze the results of the continuity tests: two of the pairs should have no continuity, and one should have continuity. If you get a different result, the switch is bad and needs to be replaced.
  6. Restore the tube connection to the switch in preparation for a second round of continuity testing.
  1. Blow gently into the tube while retesting the terminals for continuity in pairs in the same sequence as the first round of testing. You should hear the switch click when you blow into the tube. Maintain the air pressure as you test the terminals, and note the results.
  2. Analyze the results of the second round testing and compare them to those of the first round. The pairs that showed no continuity in the first round should show continuity with pressure in the tube; the pair that showed continuity in the first test should show no continuity in the second. Results other than these mean that the switch is bad and needs to be replaced.
  3. If the continuity testing does not indicate an electrical problem in the switch, reconnect the clean, straightened pressure tube to the nipple at the bottom of the tub and run the machine through a cycle to see whether the problem has been corrected.