Rheem A108 Error: Condensate Blocked

The Short Answer: Rheem ProTerra / Performance Platinum A108 is condensate blocked: the rope sensor in the heat-pump drain pan got wet. The compressor stops and the 4500 W elements take over. Kill the double-pole. Clear the drain path. Do not jumper the sensor. If the pan is dry and A108 returns, hire a licensed hybrid tech.

Search Intent & The Real Problem

EcoNet beeped. The screen says A108 — condensate blocked, unclog line. Showers may still be hot because the backup elements ran. Your bill just became an electric tank. A108 is not a tank leak, not A008 dry-fire, and not a compressor A004. It is water on the condensate rope under the evaporator, almost always a clogged, kinked, frozen, or uphill drain — same physics as a Navien condensate overflow, different machine.

Full hybrid map: Rheem heat-pump problems. AO Smith Voltex is a different OEM: Voltex codes. Noise with no A108: hybrid noise. Water at the tank jacket is a leak first — bottom of the tank.

What other guides get wrong

They decode A108 as “replace the heat pump” or paste A101–A106 thermistors onto it. A108 is the condensate rope, not a tank sensor. They tell you to unplug the two grey wires and leave them off as a repair — that is a safety bypass. They vinegar-flush a sealed refrigerant circuit. And they skip freeze: an uninsulated condensate line in a 20°F garage will A108 every January while the pan looks “fine” at noon.

Step-by-Step Troubleshooting

Step 1: Photograph A108 — do not guess the generation

EcoNet ProTerra / Performance Platinum / many Ruud and Richmond hybrids show A (active alarm) and T (transient). The jacket sheet on that tank is law.

• What to look for: Photo of A108 and the rating plate (ProTerra, Performance Platinum, Prestige hybrid, HP series). A unit that fell back to Electric may still make hot water — that is not “fixed.”
• Required tools: Phone camera. Do not clear the code until you have the picture.

Step 2: Kill 240 V, then look at the drain — not the tank

• What to look for: Condensate line from the heat-pump section: kink, crushed vinyl, stuffed into a full standpipe, no slope, algae plug, outdoor termination frozen. Cool, slightly milky water in the upper pan under the evaporator vs hot water at the tank shell or plastic drain. Cool + timed to compressor run = condensate. Hot + rust = leak; stop this page.
• Required tools: Breaker lock, flashlight, paper towel. Filter / top access only with power verified dead.

Ask where that hose actually terminates. A 20-foot loop over the tank is not a drain. Condensate pumps that died will A108 every recovery.

Step 3: Clear the line and dry the pan — one honest reset

• What to look for: Disconnect the condensate hose at the pan outlet (power still off). Blow or wet/vac toward the termination, not back into the evaporator. Standing water on the rope: dry the pan and the sensor with a towel. Re-route so it slopes down to an approved drain. Frozen line: thaw the pipe; do not torch the hybrid.
• Required tools: Wet/vac, towel. No garden hose into the live coil. No refrigerant gauges.

Restore 240 V once after the pan is dry and the line runs. If A108 is gone and the compressor actually starts (not just Electric), you found the clog. Daily A108 clears are keep resetting, not a drain.

Step 4: Filter, closet, and a fan that never stops

• What to look for: Evaporator filter packed so the coil sweats into a pan that cannot keep up. Closet so tight the fan screams. Condensate secondary pan or leak puck in a flood pan that is a different sensor. A fan that never stops after a clear A108 is fan keeps running, not this rope.
• Required tools: Filter (power off). Level on the jacket — a leaning hybrid dumps condensate to the wrong corner.

Never reset an ECO on an empty tank — turned on without water. Meter an element only with power dead — 4500 W / 240 V reads ~12–13 Ω.

Step 5: Dry pan, open line, A108 returns — sensor or board

• What to look for: Pan dry, termination clear, water runs through the hose, sensor sitting in its pocket under the coil — and EcoNet still A108. Rope that reads continuity while dry is failed. Board that alarms with a proven-open sensor is the PCB. Both are licensed. A tech may isolate the connector as a test. You may not leave the safety unplugged.
• Required tools: On a licensed truck: meter on the rope, OEM sensor, leak-detection at the tank if they also find potable water.

House static over ~80 psi plus a dumping T&P (150 psi / 210°F) is pressure, not A108. Oil film or a sweet chemical smell at the top is sealed-system — not a condensate hose.

When DIY Ends: Calling a Licensed Pro

You may photograph A108, kill the double-pole, unkink or wet/vac a customer-accessible condensate hose, dry the upper pan, clean the filter, and power-cycle once. You may not jumper the rope, open process ports, or run Electric-only on a leaking shell. Repeating A108 on a dry pan, a frozen line you cannot reach, a dead condensate pump, or a wet tank jacket is a same-day licensed call — heat-pump techs and plumbers are not interchangeable, so hire one who will actually work on this ProTerra.

Frequently Asked Questions

Q: What does A108 mean on a Rheem water heater? A: On Rheem/Ruud/Richmond hybrids it is condensate blocked — the rope sensor in the heat-pump drain pan got wet. The compressor locks out and elements take over. It is not a tank thermistor code and not tankless 11/12.

Q: Why is my Rheem hybrid still heating on A108? A: Backup 4500 W elements. That is Electric mode, not a repair. Clear the drain path. If A108 returns on a dry pan, hire a licensed hybrid tech — do not keep resetting.

Q: Can I unplug the A108 condensate sensor to clear the alarm? A: No. That is a safety bypass. Dry the pan, clear the line, one power cycle. A licensed tech may isolate the sensor only as a test, then replace the failed part.