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Brand-specific HVAC error codes decoded: ranked causes, safe DIY checks, honest repair costs, and when to call a licensed technician.
Error code charts
Lennox Furnace codes
34 codes Carrier Furnace codes
30 codes Goodman Furnace codes
24 codes Trane Furnace codes
23 codes York Furnace codes
21 codes Bryant Furnace codes
16 codes Rheem Furnace codes
13 codes Amana Furnace codes
9 codes American Standard Furnace codes
8 codes Carrier Heat Pump codes
6 codes Rheem Heat Pump codes
6 codes Goodman Heat Pump codes
5 codes Lennox Heat Pump codes
5 codes Trane Heat Pump codes
5 codes York Heat Pump codes
5 codes
By brand
Carrier 37 codes Goodman 30 codes Trane 28 codes Lennox 39 codes York 26 codes Rheem 19 codes Bryant 16 codes Amana 9 codes Honeywell 1 code American Standard 8 codes
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Carrier Heat Pump — Ice on outdoor unit Carrier Heat Pump Ice on Outdoor Unit: Causes & Fixes Ice on your Carrier heat pump outdoor unit? Learn normal frost vs. problem ice, the main causes, safe checks, and repair costs from $0 to $2,500+. Carrier Heat Pump — Stuck in defrost mode Carrier Heat Pump Stuck in Defrost Mode: Causes & Fixes Carrier heat pump stuck in defrost? Learn the causes (defrost board, sensor, reversing valve, relay), safe checks, and repair costs from $0 to $1,800+. Goodman Heat Pump — Stuck in defrost mode Goodman Heat Pump Stuck in Defrost Mode: Causes & Fixes Goodman heat pump stuck in defrost? Learn the causes (defrost board, sensor, reversing valve, refrigerant), safe checks, and repair costs. Lennox Heat Pump — Stuck in defrost mode Lennox Heat Pump Stuck in Defrost Mode: Causes & Fixes 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+. Rheem Heat Pump — Ice on outdoor unit Rheem Heat Pump Ice on Outdoor Unit: Causes & Fixes Ice on a Rheem heat pump outdoor unit: normal frost vs. a real problem, the main causes (airflow, drainage, low charge), safe fixes and repair costs. Rheem Heat Pump — Stuck in defrost mode Rheem Heat Pump Stuck in Defrost Mode: Causes & Fixes Rheem heat pump stuck in defrost? Learn the likely causes (defrost board, coil sensor, reversing valve), safe checks, and repair costs from $0 to $2,500. Trane Heat Pump — Stuck in defrost mode Trane Heat Pump Stuck in Defrost Mode: Causes & Fixes Trane heat pump stuck in defrost? Learn the causes (defrost board, sensor, reversing valve, relay), safe checks, tech diagnosis and repair costs. York Heat Pump — Stuck in defrost mode York Heat Pump Stuck in Defrost Mode: Causes & Fixes York heat pump stuck in defrost? Learn the causes (sensor, board, reversing valve, relay), safe checks, technician fixes, and repair costs. Carrier Heat Pump — Frozen and not defrosting Carrier Heat Pump Frozen and Not Defrosting: Causes & Fixes Carrier heat pump iced over and not defrosting? Learn the causes (airflow, runoff, defrost sensor, board, low charge), safe fixes and repair costs. Goodman Heat Pump — Ice on outdoor unit Goodman Heat Pump Ice on Outdoor Unit: Causes & Fixes Ice on your Goodman heat pump outdoor unit: normal frost vs. a real problem, the likely causes, safe homeowner checks, and typical repair costs. Lennox Heat Pump — Frozen and not defrosting Lennox Heat Pump Frozen and Not Defrosting: Fixes & Cost Lennox heat pump iced over and not defrosting? Learn the causes (water drips, defrost sensor, board, reversing valve), safe checks, and repair costs. Lennox Heat Pump — Ice on outdoor unit Lennox Heat Pump Ice on Outdoor Unit: Causes & Fixes 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+.Looking for a specific code? Search the full library or browse furnaces, air conditioners and heat pumps.