E20
Bryant
IAQ Accessory Control Fault
Thermostat displays E20 and indicates an indoor air quality (IAQ) accessory fault; air purifier or UV light control may be disabled.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Disconnected or failed Bryant air purifier (e.g., Evolution Air Purifier) control wiring, Incorrect IAQ accessory configuration in thermostat, Failed IAQ accessory power or control module, Blown low-voltage fuse due to IAQ wiring short
How to Fix / Troubleshooting
Safety first: Turn off power to the indoor unit and IAQ accessories at the breakers before working on wiring.
Steps to troubleshoot:
- 1. Verify configuration: In the thermostat installer menu, ensure only installed IAQ accessories are enabled.
- 2. Inspect IAQ wiring: At the indoor unit, check the connections to the Bryant air purifier or UV system. Tighten loose wires and repair any damaged insulation.
- 3. Check IAQ power: Confirm that the IAQ accessory has its required power source (line voltage or low voltage) and that any inline fuses are intact.
- 4. Replace accessory module if needed: If wiring and power are correct but the IAQ device does not respond, its control module may need replacement by a technician.
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Repair Difficulty
Medium
3/5
Required Part
Bryant Evolution Air Purifier Control Module
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