System Diagnosis
Line Voltage High. Incoming line voltage rose above allowed thresholds; unit will not operate or will shut down while active.
Carrier | Heat Pumps
Error Code 15-94
Troubleshooting guide for the Carrier Heat Pumps system fault 15-94.
Disclaimer: This information is for general reference. Error codes can vary by model and production year. Always refer to your machine's specific manual and the information printed on the unit itself.
Potential Causes & Solutions
- Measure supply voltage at disconnect.
- Check for utility overvoltage condition.
- Inspect for open neutral on single-phase supply.
- Contact utility company if supply voltage is consistently high.
Verify Before Replacing Parts
- Confirm the exact Carrier model family and heat pumps context before acting on a generic code description.
- Start with line voltage, low voltage, and board output checks in sequence so the fault is isolated cleanly.
- Inspect connectors, relay outputs, and any recently replaced electrical parts for mismatch or loose fit.
- After the correction, run the system long enough to confirm the code does not return under normal load.
Field Signals to Confirm
What usually confirms it
Missing voltage, inconsistent outputs, or a fault that changes when a connector is reseated.
What can fool you
Intermittent power quality and field wiring problems can mimic a failed board.
When to Escalate the Call
- You have unstable supply power, repeated fuse failures, or signs of board damage.
- The failure path involves multiple boards or field-modified wiring.
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