A. O. Smith Hybrid Water Heater Problems and Codes

The Short Answer: An A. O. Smith hybrid (Voltex) heater has a heat pump on top and two electric elements inside the tank. When it stops heating, the display usually says why: a dirty air filter, a dry tank, an element circuit, a sensor, low voltage, or a compressor fault. Filter cleaning and mode settings are owner tasks. Element, sensor, and refrigerant faults need a technician.

First, which display do you have?

A. O. Smith has used two code styles on its hybrid heaters, and the same problem is shown differently on each:

• Letter codes (such as EUC, SF, Edr) on earlier models, listed in A. O. Smith’s use and care guide 326880 (opens in a new tab).
• Three-digit codes with a flashing alert icon (such as 001, 021, 080) on newer smart models, some with leak detection and an automatic shut-off valve, listed in use and care guide 100361198 (opens in a new tab).

The rating plate model number and the manual in the pocket on the heater confirm which list applies. If you see a code that is in neither list, A. O. Smith asks owners to call its technical assistance line.

What the common codes mean

Two letter codes are not faults. ICE means the heat pump is defrosting. HPO means the heat pump is outside its operating range, typically because the room is too cold or hot for it; the elements take over until conditions change.

Owner fixes that clear many complaints

Clean the air filter. The filter on top of the unit catches dust and lint before air reaches the evaporator coil. A clogged filter slows heating, can make the compressor cycle, and triggers the filter code. Switch off the breaker, slide the filter out as your manual shows, rinse or vacuum it, let it dry, and refit it.

Check the mode. A heater left in Vacation mode will not recover. Heat-pump-only (Efficiency) mode is the cheapest to run but recovers slowly after heavy use. A. O. Smith recommends Hybrid mode for most homes because it uses the elements when demand is high.

Give it air. The heat pump pulls heat from the surrounding air. In a small closet without louvered doors, or a garage near freezing, it will struggle. The manual lists minimum clearances and room size requirements.

Check the condensate drain. The heat pump produces condensate, which drains through a hose. A kinked hose, a hose that runs uphill, or a failed condensate pump causes drainage codes and water in the pan. Make sure the unit is level, which A. O. Smith lists as the first step for the condensate code.

Refill before restoring power. If the tank was drained, open a hot tap and let it run until water flows steadily before switching the breaker back on. The dry-fire code exists because energizing elements in an empty tank destroys them.

Slow recovery is not always a fault

If the heater shows no code but hot water runs out, compare the pattern with the mode. Heat-pump-only mode can take several hours to reheat a full tank, more in a cold room. Several short draws in a row (A. O. Smith calls this “stacking”) can also leave lukewarm water at the tap even when the tank’s average temperature looks right. Our guide to heat pump water heater location explains how the space affects output.

What the technician will check

For element codes, the technician isolates power and checks element and wiring resistance and connections at the control board. For sensor codes, they check the connector and wiring for each sensor before replacing it. Compressor, suction-pressure and fan codes need a technician who works on sealed refrigeration systems; A. O. Smith’s manual directs owners to its technical assistance line for these. Refrigerant work cannot be done by an owner.

Repair or replace

Filters, elements, sensors, condensate pumps, and anode rods are repairs. A compressor or sealed-system failure may be covered by the heat pump warranty, so check the terms before paying for it. Water leaking from the tank shell, not a fitting, means the heater needs to be replaced. Noise without a code is covered in hybrid water heater noise.

Frequently Asked Questions

Q: Can I run my A. O. Smith hybrid in Electric mode while I wait for a repair? A: Yes, if the fault is in the heat pump and the elements work. Electric mode costs more to run, so treat it as temporary.

Q: Why does the display say ICE? A: The heat pump is defrosting its coil. It is normal in cool spaces and clears on its own.

Q: What does 044 mean on a newer model? A: A. O. Smith lists 044 as a depleted anode on models with that feature. The anode protects the tank from corrosion, so have it replaced rather than ignored.