How Multiple Pressure Switches Work (And What They Reveal)

Most techs treat pressure switches like they “diagnose parts”—but they don’t. They only tell the control board one thing: permission to run, yes or no.

In this video I break down how multiple pressure switch furnaces actually work (two switches, and even three), why the board wants more than one confirmation, and how to read the timing of when that permission gets pulled—because that’s where the real clues start.

If you want to stop guessing and start understanding what the board is looking for, this will connect a lot of dots.
0:00 – Foundation: What Pressure Switches Actually Do
1:01 – Why Some Furnaces Have Two (or More) Pressure Switches
2:06 – Following the Hoses: What the Board Is Actually Watching
3:38 – Using Multiple Switches as Diagnostic Clues
6:40 – Timing Clues & Heat Exchanger Red Flags