Carrier 58MVP Error Code Rapid Flashing: Reversed Line Voltage Polarity
What Does Code Rapid Flashing Mean?
A rapidly flashing LED on the Carrier 58MVP indicates that the 115-volt line voltage polarity is reversed — the hot and neutral wires are connected backwards. The control board checks polarity at startup and will not operate the furnace normally until this is corrected.
Reversed polarity is an electrical wiring issue, not a furnace malfunction. It can occur if the furnace was recently installed or serviced and the wires were reconnected incorrectly, or if the electrical outlet or junction box feeding the furnace has reversed wiring. In older homes, miswired outlets are not uncommon.
This is not something that can be safely fixed as a DIY project because it involves working with 115-volt line voltage. An electrician or HVAC technician needs to identify where the polarity reversal occurs — whether at the furnace disconnect, the circuit breaker panel, or somewhere in between — and swap the hot and neutral connections to their correct positions.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Hot and neutral wires reversed at furnace connection | Most common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- Immediately when this code appears — reversed polarity is an electrical wiring issue that requires a licensed electrician or HVAC technician
✓ Verified against manufacturer service manual — March 2026