Bryant 355MAV Error Code 15: Blower Motor Lockout
What Does Code 15 Mean?
Status code 15 on the Bryant 355MAV indicates a blower motor lockout. The control board detected that the blower failed to reach 250 RPM or failed to communicate within 30 seconds after being turned on, and this happened in two successive heating cycles. After two consecutive failures, the control enters a lockout state that will auto-reset after 3 hours.
The Bryant 355MAV uses an ECM (electronically commutated motor) variable speed blower, which communicates digitally with the control board. When the motor cannot reach the required speed or the communication link fails, the control board cannot verify that the blower is moving air. Without confirmed blower operation, the furnace cannot safely operate because heat would build up in the heat exchanger without being distributed.
The most common cause is a failed ECM blower motor. These motors contain built-in electronics that can fail independently of the motor windings. A wiring problem between the control board and the blower motor module is the second most likely cause. In either case, the diagnosis requires testing with specialized equipment, and replacement typically requires a qualified HVAC technician.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Failed ECM blower motor | Most common | ✗ Call a pro → |
| Wiring issue between control board and blower motor | Common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- The furnace shows code 15 and the blower does not run during heating cycles
- The blower motor hums but does not spin, or makes unusual noises when it attempts to start
✓ Verified against manufacturer service manual — March 2026