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Tyler ScottJul 31, 2025
How to fix a Johnson Controls Controller that is OFF?
- DDonald PriceJul 31, 2025
If the Johnson Controls Controller is OFF, it could be due to several reasons. First, a shorted transformer might be the cause. Second, a 24 VAC powered sensor or SA Bus device might not be wired with the same polarity as the controller. To resolve this, ensure the polarity of ~24 V COM / ICOM / + 15VCOM/SA BUS COM on the controller, auxiliary devices, and I/O is consistent. Also, make sure that OUT1-OUT3 terminals of binary outputs are not connected to ~24 VAC COM, and verify that OCOM1-OCOM3 are not connected to ~24 VAC HOT, as these terminals are internally sourced. Use an ohm-meter to verify and resolve any short circuits. Finally, reset the breaker/fuse or replace the transformer.