When customer’s contact us about troubleshooting a snap disc thermostat that is found in a piece of their equipment one of the first things we ask the customer is if the done a thermostat continuity test. This will tell us if the high limit has been reached, and it’s simple! Give us a call for for more information or visit our online store to purchase.

Before testing the continuity, you’ll need a tool to preform the test. A continuity tester might sound like a fancy piece of equipment, but you can actually find a simple one on Amazon that’s fairly inexpensive.

  1. Unplug the equipment from incoming power
  2. Remove wires from the thermostat
  3. Run a continuity test across the terminals
    1. If the tester’s light doesn’t turn on the switch’s circuit is open and the high limit has been reached and the thermostat needs to be reset.
    2. If the tester’s light does turn on the switch’s circuit is closed and the limit has not been reached. Please be sure the system’s temperature reached the high limit, and if problem still occurs, click here to contact us.

A switch that opens or closes at a cold temperature is a little more time consuming to test, but still fairly easy. To test a cold switch, just put it in the freezer. After 10-15 minutes, take the switch out and test continuity. You can then let the switch warm up naturally or use a lighter to speed up the process.

If your testing proves successful, then you know that your switch is working.

If a reset is needed, resetting the snap disc thermostat depends on the type of thermostat.

If it’s an automatic reset thermostat switch, bring the temperature in the system back to normal to reset the switch. Automatic reset temperature switches have a set opening and closing temperature. For example, if a switch opens at 125°F and closes at 105°F, then you would need to bring the temperature in your system down to 105°F or below to get the switch to reset.

If it’s a manual reset thermostat switch, press the red button found on the thermostat switch to reset. Manual reset thermostat switches will not reset by themselves, and require human intervention to reset.

Loose Mount Manual Reset

A manual reset temperature switch

If it’s a one shot thermostat switch, the switch needs to be replaced. Click here to contact us. For more information about our switches, take a look at our catalog.

Contact our technical support today!


The superior controls manufactured by Senasys have a history of solid performance in many industries. From 22.5 mm selectors, to the four quadrant lighted feedback CMC controls, almost any switching need can be, and has been utilized in a variety of applications. Select a group below for more information. When you have found a switch that fits your needs, simply fax or email your specs to us and let our highly trained engineers find the most efficient configuration for your applications.

Custom Soltutions

Senasys products are designed & manufactured to meet the needs of original equipment manufacturers worldwide.

Made in U.S.A.

Senasys products are designed & manufactured in Eau Claire, Wisconsin, U.S.A.