Thermostat shows correct temperature but house feels too humid or too dry

Safety first: Turn off power to furnace/air handler and accessories before working on wiring.

• Step 1 – Check humidity setpoints: Verify desired humidity levels are set correctly in the thermostat (typically 30–50% RH).
• Step 2 – Confirm accessory operation: When humidity is out of range, check if the humidifier or dehumidifier actually runs. If not, inspect wiring and configuration.
• Step 3 – Compare humidity readings: Use a separate hygrometer to verify the thermostat’s humidity reading. If significantly off, the thermostat may need replacement.
• Step 4 – Evaluate capacity: If accessories run continuously but humidity remains uncontrolled, the equipment may be undersized or there may be building envelope issues.

When to call a professional: For wiring verification and capacity evaluation, contact an HVAC technician.