Bryant 315AAV Error Code 31: High-Heat Pressure Switch Open or Relay Did Not Close
What Does Code 31 Mean?
Status code 31 on the Bryant 315AAV indicates a high-heat pressure switch fault. The integrated furnace control attempted to verify that the high-heat pressure switch closed (made contact) to confirm that the inducer is creating sufficient negative pressure for safe venting, but the switch did not close within the required time.
The service documentation identifies three possible causes: a high-heat pressure switch stuck in the open position, a defective control relay, and a reversed gas valve. A stuck-open pressure switch may be caused by a failed switch diaphragm or by obstructed pressure tubing preventing the switch from sensing the inducer pressure. A defective control relay means the board's internal switching component that helps control the high-heat circuit has failed. A reversed gas valve can affect pressure sensing by disrupting normal airflow through the heat exchanger.
Because the 315AAV is a two-stage furnace, the high-heat pressure switch (code 31) and low-heat pressure switch (code 32) are separate components. A technician will identify which switch is at issue and test it along with the associated tubing and relay.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| High-heat pressure switch stuck open | Most common | ✗ Call a pro → |
| Defective control relay | Common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- Contact a technician to diagnose the high-heat pressure switch, control relay, and gas valve orientation
- Do not substitute a non-OEM pressure switch; the 315AAV requires switches calibrated to its specific high-heat inducer pressure
✓ Verified against manufacturer service manual — March 2026