Should a physical jumper be used with the Alarm.com Smart Thermostat HD (ADC-T40K-HD)?
No. Using a physical jumper can cause physical damage to the thermostat over time and cause the wire detection to complete incorrectly. The Smart Thermostat HD has an internal jumper between RH and RC. The internal jumper closes if there is only one wire in RH and nothing in RC.
When wire detection is completed incorrectly due to a physical jumper between RH and RC, the following HVAC problems can occur once the physical jumper is removed:
- The air conditioner will not turn on when the thermostat is in Cool Mode.
- Fan control will not function despite thermostat settings.
- Heat Pump functionality will not follow thermostat settings.
To re-configure the Smart Thermostat HD after removing a physical jumper:
- Remove the physical jumper.
- Verify the R wire is in RH.
- Place the front plate on the thermostat.
- Tap
. - Tap Installer Settings.
- In Installer Settings, tap Reset Wiring.
- Wire detection will begin, and the internal jumper will be applied to ensure the thermostat continues to operate effectively.