{"id":13719,"date":"2025-03-19T06:52:48","date_gmt":"2025-03-19T13:52:48","guid":{"rendered":"https:\/\/www.appliancepartspros.com\/b\/?p=13719"},"modified":"2026-07-14T10:49:03","modified_gmt":"2026-07-14T17:49:03","slug":"how-to-test-and-replace-a-furnace-limit-switch","status":"publish","type":"post","link":"https:\/\/www.appliancepartspros.com\/b\/how-to-test-and-replace-a-furnace-limit-switch\/","title":{"rendered":"How to test and replace a furnace limit switch"},"content":{"rendered":"","protected":false},"excerpt":{"rendered":"

Learn how to test and replace a furnace limit switch with easy-to-follow steps to keep your furnace running smoothly and efficiently.<\/p>\n","protected":false},"author":3,"featured_media":13762,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_yoast_wpseo_focuskw":"How to test and replace a furnace limit switch","_yoast_wpseo_title":"%%title%% %%page%%","_yoast_wpseo_metadesc":"Learn how to test and replace a furnace limit switch with easy-to-follow steps to keep your furnace running smoothly and efficiently.","_aviaLayoutBuilderCleanData":"[av_image src='https:\/\/www.appliancepartspros.com\/b\/wp-content\/uploads\/2025\/01\/Updated-blog-rectangle-17.jpg' attachment='13763' attachment_size='full' copyright='' caption='' styling='' align='center' font_size='' overlay_opacity='0.4' overlay_color='#000000' overlay_text_color='#ffffff' animation='no-animation' hover='' appearance='' link='' target='' title_attr='' alt_attr='' lazy_loading='disabled' id='' custom_class='' av_element_hidden_in_editor='0' av_uid='av-3uqajb' admin_preview_bg=''][\/av_image]\r\n\r\n[av_textblock size='' av-medium-font-size='' av-small-font-size='' av-mini-font-size='' font_color='' color='' id='' custom_class='' av_uid='av-m5qti67r' admin_preview_bg='']\r\nHaving trouble with your furnace and think the limit switch might be the issue? Replacing a furnace limit switch is something you can handle with a little help. We'll walk you through the steps so your furnace stays safe and runs smoothly.<\/span>\r\n\r\nThe info here might not match your specific furnace model exactly. We aim to provide useful tips for all sorts of DIY repairs, but different models can vary in troubleshooting, error codes, parts, etc. For the best advice, we recommend checking your model's manual, or feel free to <\/span>reach out to us<\/span><\/a> if you have questions.<\/span><\/em>\r\n\r\n[lwptoc numeration=\"none\"]\r\n

\u26a0\ufe0f Smell gas?<\/b> Stop \u2014 get outside, then call your gas utility (or 911) from there. Full safety notes below<\/a>.<\/div>\n\n

What is the furnace limit switch?<\/span><\/h2>\r\nYour furnace's limit switch plays a key role in keeping things safe by keeping an eye on the temperature inside. It stops the system from overheating by shutting off the burner or heating element if things get too hot. If the switch isn't working right, it might stop the furnace from running or fail to shut it down when it should, which can be a safety concern.<\/span>\r\n\r\nRead more: <\/b>12 things you should know about portable space heaters<\/b><\/a>\r\n

How to test the limit switch<\/span><\/h2>\r\nBefore starting replacement, it's a good idea to test the limit switch to make sure it's causing the issue. Here's what you can do:<\/span>\r\n

1. Check for airflow issues<\/span><\/h3>\r\nSometimes, the limit switch might trip because the furnace is overheating due to poor airflow:<\/span>\r\n
    \r\n \t
  1. Make sure all the warm air registers in the house are open and not blocked.<\/span><\/li>\r\n \t
  2. Check that return vents aren't covered up by furniture, rugs, or curtains.<\/span><\/li>\r\n<\/ol>\r\n

    2. Inspect the limit switch<\/span><\/h3>\r\nThe limit switch is typically near the top of the furnace burner assembly. Once you've located it:<\/span>\r\n
      \r\n \t
    1. Look over the switch for any signs of damage like cracks or rust.<\/span><\/li>\r\n \t
    2. Make sure it's clean and not covered in dust or grime. If it is, give it a gentle wipe with a soft cloth.<\/span><\/li>\r\n<\/ol>\r\n

      3. Perform an operational test<\/span><\/h3>\r\nTo check if the limit switch is working when the furnace is running:<\/span>\r\n
        \r\n \t
      1. Start up your furnace and set the thermostat higher than the room temperature.<\/span><\/li>\r\n \t
      2. Let the furnace start and run for a bit.<\/span><\/li>\r\n \t
      3. After it has been running for a few minutes, turn the thermostat down.<\/span><\/li>\r\n \t
      4. Wait 3 to 5 seconds and listen for a click.<\/span><\/li>\r\n<\/ol>\r\nIf you hear the click, the limit switch is telling the furnace to shut off the burners or heating element and is working correctly.<\/span>\r\n

        4. Conduct a continuity test<\/span><\/h3>\r\nIf you have a multimeter, you can do a continuity test on the limit switch:<\/span>\r\n
          \r\n \t
        1. Make sure the furnace is completely powered off to avoid any shocks.<\/span><\/li>\r\n \t
        2. Set your multimeter to the continuity setting. If you're not sure how to use a multimeter, check out some resources on our <\/span>repair help<\/span><\/a> page.<\/span><\/li>\r\n \t
        3. Carefully unplug the wires connected to the limit switch terminals.<\/span><\/li>\r\n \t
        4. Touch the multimeter probes to each terminal on the switch.<\/span><\/li>\r\n \t
        5. If the multimeter beeps or shows continuity, the switch is good. If not, the switch needs to be replaced.\u00a0<\/span><\/li>\r\n<\/ol>\r\nRead more: <\/b>Your guide to choosing a space heater<\/b><\/a>\r\n

          Safety precautions<\/span><\/h2>\r\nSafety should always be a priority when working on any appliance. Here are a few practical tips to help you stay safe:<\/span>\r\n