Uploaded June 2026 | Updated September 2026, 2 weeks ago
Limit switches are small, inexpensive components — but if you don't understand what they're doing or why they're tripping, they can turn a simple service call into a frustrating diagnostic loop. In this video, our techs walk through limit switch troubleshooting from the ground up, covering how bimetal disc switches actually work, why manual reset switches often won't reset after you push them, and what that tells you about the condition of the system.
We also get into open-on-rise switches more broadly — high pressure switches, thermal protectors, and the patterns that connect them all. When any of these devices trip repeatedly, the switch itself is rarely the whole story. Dirty filters, restricted airflow, low CFM, dirty coils, overcharge, moisture freezing at the expansion valve — these are the kinds of root causes worth investigating before you call the job done.
On the topic of bypassing safeties: there's a right way to handle a situation where a switch has failed and the customer needs equipment running. Temporary workarounds exist, but you should never leave a system — especially one with electric heat strips — with no protection in place. If you bypass, at minimum leave another safety in the circuit, document it clearly in your notes, and have an honest conversation with the customer about next steps.
Read all the tech tips, take the quizzes, and find our handy calculators at hvacrschool.com or the HVAC School Mobile App on the Google Play Store (hvacrschool.com/play-store) or App Store (hvacrschool.com/app-store).
Limit switches are small, inexpensive components — but if you don't understand what they're doing or why they're tripping, they can turn a simple service call into a frustrating diagnostic loop. In this video, our techs walk through limit switch troubleshooting from the ground up, covering how bimetal disc switches actually work, why manual reset switches often won't reset after you push them, and what that tells you about the condition of the system.
We also get into open-on-rise switches more broadly — high pressure switches, thermal protectors, and the patterns that connect them all. When any of these devices trip repeatedly, the switch itself is rarely the whole story. Dirty filters, restricted airflow, low CFM, dirty coils, overcharge, moisture freezing at the expansion valve — these are the kinds of root causes worth investigating before you call the job done.
On the topic of bypassing safeties: there's a right way to handle a situation where a switch has failed and the customer needs equipment running. Temporary workarounds exist, but you should never leave a system — especially one with electric heat strips — with no protection in place. If you bypass, at minimum leave another safety in the circuit, document it clearly in your notes, and have an honest conversation with the customer about next steps.
Read all the tech tips, take the quizzes, and find our handy calculators at hvacrschool.com or the HVAC School Mobile App on the Google Play Store (hvacrschool.com/play-store) or App Store (hvacrschool.com/app-store).
