State Hybrid Water Heater ECC Code
On this page (5 sections)
The Short Answer: On hybrid heat pump water heaters that use the letter-code display, ECC means the heat pump compressor is not functioning. The manufacturer’s corrective action is to call technical support, not a homeowner fix. The electric elements can usually still heat the tank, so you may have hot water, but the heater will use more electricity until the heat pump is repaired.
What the code means, from the manual
The A. O. Smith hybrid use and care guide (opens in a new tab), which uses the same display codes found on many State-branded hybrids, lists ECC as “Heat pump compressor is not functioning” and tells owners to call the Technical Assistance Hotline. It does not list a filter cleaning or reset for ECC.
Newer State hybrids show numeric codes instead. State’s current installation and use and care guide (opens in a new tab) lists 084 for the same condition, again with a call to technical support, and explains that the control switches into “Limp Mode 3”: when the heat pump is unavailable, both electric elements cover the call for heat. Older State hybrids with a text display show a heat-pump fault message rather than a code.
Because State has used more than one display generation, confirm the code on the chart in the manual for your model number before acting on it.
Codes that are easy to confuse with ECC
These are listed in the same A. O. Smith guide. Several of them do have owner-level steps.
| Display | Meaning (per the guide) | Who acts |
|---|---|---|
| ECC | Heat pump compressor not functioning | Technical support or a qualified technician |
| ECF | Compressor starting and stopping frequently | Owner can clean the air filter and check the space requirements; call if it persists |
| SF | Air filter is dirty | Owner cleans the filter per the manual |
| ECL | Heat pump suction pressure too low | Technical support |
| EDH | Compressor discharge temperature too high | Technical support |
| EUC / ELC | Upper or lower element not functioning | Qualified technician |
| Edr | Not enough water in the tank | Owner runs hot taps until water flows steadily |
| HPO | Ambient air outside the heat pump’s range (below 45°F or above 120°F) or a very cold tank | Not a fault; the heat pump waits |
| ICE | Defrost cycle | Normal |
What you can do now
- Photograph the display and write down the model and serial number from the data plate. Support will ask for both.
- Check the air filter and surroundings. A clogged filter or a small, closed room does not cause ECC by the manual’s definition, but a starved heat pump can run hot, and the guide lists both as maintenance items. Clean the filter as the manual describes and clear boxes away from the air inlet and outlet.
- Check the condensate line for kinks or a disconnected tube, and that any condensate pump is plugged in.
- Keep the tank full. Never run the heater after draining it without first filling it and running hot taps until water flows without air.
Leave the covers on. The compressor, its start components, wiring, and refrigerant circuit are not owner-serviceable.
What the technician will check
A technician working with the manufacturer will usually confirm whether the compressor tries to start, check its electrical supply and start components (such as the run capacitor), look at fan operation, and check for signs of a refrigerant leak such as oil residue. Results tend to fall into three groups:
- Electrical start problem: often a repair of a component on the heat pump.
- Compressor or sealed-system failure: sealed refrigerant systems on these heaters are commonly handled as a warranty claim or a replacement decision rather than a field repair. Check the warranty sheet; heat pump components often carry a different term from the tank.
- Tank leaking: replacement, regardless of the code. See water leaking from the bottom of the tank.
For other hybrid codes and noises, see A. O. Smith hybrid water heater problems and hybrid water heater noise.
Frequently Asked Questions
Q: Can I keep using the heater with an ECC code? A: Usually, yes. The elements take over, which keeps hot water available but raises electricity use. Arrange service rather than running on elements indefinitely.
Q: Will turning the power off and on clear ECC? A: It may clear the display briefly, but the manual’s action for ECC is to call technical support. If the compressor cannot run, the code will return.
Q: Is ECC the same as the SF filter code? A: No. SF is a dirty-filter reminder that you can clear by cleaning the filter. ECC reports that the compressor itself is not working.
Manuals and supporting references
These links distinguish general safety information from model-specific documentation. A manual directory helps you locate your unit’s instructions; it does not establish that every model uses the same parts, codes, or test values.
- A. O. Smith: Residential Hybrid Electric Heat Pump Water Heater Use and Care Guide (diagnostic codes) (opens in a new tab)Hybrid heat pump models covered by this guide, which use the ECC, ECF, SF, Edr letter-code display.
- State: Hybrid Electric Heat Pump Water Heater Installation Instructions and Use & Care Guide (opens in a new tab)Current State hybrid models with numeric codes; code 084 is the compressor-not-functioning equivalent, and Limp Mode 3 is described.
- A. O. Smith: standard electric no-hot-water diagnostic chart (opens in a new tab)Professional diagnostic context for standard electric storage heaters; not instructions to open or test your appliance.
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