Lennox Heat Pump error codes
5 Lennox heat pump codes and problems, each with ranked causes, safe homeowner checks and honest repair costs. Count the flashes or read the code on your control board, then find it below. Legends vary by board revision, so confirm against the label inside your unit's door.
| Code | What it means | Severity |
|---|---|---|
| Frozen and not defrosting | Lennox heat pump iced over and not defrosting? Learn the causes (water drips, defrost sensor, board, reversing valve), safe checks, and repair costs. | Call a pro |
| Ice on outdoor unit | Ice on your Lennox heat pump's outdoor unit? Learn normal frost vs. problem icing, the likely causes, safe checks, and repair costs from $0 to $3,000+. | Call a pro |
| Not cooling | Lennox heat pump not cooling? Ranked causes like reversing valve, capacitor, low refrigerant and dirty coils, safe checks, and honest repair costs. | Call a pro |
| Not heating | Lennox heat pump not heating? Causes like thermostat setup, defrost, low refrigerant or stuck reversing valve, safe checks, and repair costs. | Call a pro |
| Stuck in defrost mode | Lennox heat pump stuck in defrost? Learn the causes (defrost board, sensor, reversing valve, relay), safe checks, and repair costs from $0 to $1,500+. | Call a pro |
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