Code: 68🔥 Rheem Gas Furnace

Rheem Furnace Code 68: No Communications with the Blower Motor

Reviewed 2026-10-23 · Based on 3 manufacturer & service sources

What the code means

Rheem's fault code label for its serial communicating gas furnaces lists 68 under blower faults as "No Communications with Blower Motor." These furnaces use a communicating ECM blower motor that takes its speed commands from the integrated furnace control over a low-voltage control cable, while line voltage powers the motor through a separate 5-pin connector. The (-)96V installation manual says that if the motor isn't communicating properly with the furnace control, code 68 is displayed any time there is a call for cooling, heating or continuous fan. The 802V manual lists "No Blower Communications" (68) as a fault where the furnace will not operate in any mode. So 68 isn't a burner, flame or venting problem: it means the board sent a blower request and got no answer from the motor.

Likely causes

Safe DIY checks

⚠ Before you start

Turn off power at the furnace/HVAC service switch and the breaker before opening panels. Shut the gas valve before any work near the burners, and never disconnect or alter the gas line. If you smell gas, leave the house and call your gas utility.

  1. Write down the code and anything else the display shows. On these furnaces the display can alternate between 10 (one-hour lockout) and the fault behind it, and fault history shows at power-up, most recent first.
  2. Turn the furnace off at its power switch or breaker, wait about 30 seconds, and turn it back on with the blower door fully closed and latched. A door that's not pressing the door switch keeps the motor from getting power.
  3. With the power off, open the blower compartment and look at the motor. Check that the 5-pin power plug and the smaller control plug are pushed all the way onto the motor, and that the control cable is plugged in firmly at the furnace control board. Look for pinched, chafed or burned wires.
  4. Restore power, close the door, and run the fan from the thermostat. If 68 comes back right away on any call for heat, cooling or fan, the motor still isn't answering, and the next checks are live-voltage tests.
  5. Leave the furnace's memory card where it is. Rheem warns that the card holds model data the furnace needs and must stay with the furnace, even if the control board is replaced.

🛠 When to call a pro

  • Code 68 returns after power-cycling and reseating the connectors. The furnace won't heat, cool or run the fan until it's cleared, so in cold weather it's an urgent call.
  • Checking line voltage at the motor: Rheem's manual has the tech verify 115-120 VAC between pins 4 and 5 of the 5-pin connector with the door switch closed, then fix the wiring if there's none.
  • Testing the motor directly: with the control plug pulled from P5 on the furnace control, applying 24 VAC to pins 3 and 4 should start the motor at about 75% of capacity. If it runs well the motor probably isn't the problem; if it doesn't and the wiring is good, the manual says the motor likely needs replacing.
  • Replacing the ECM motor or the furnace control board. Use the exact Rheem/Ruud replacement for your model, and never a control board taken from another furnace, which Rheem says can load the wrong model data.
  • You smell gas or a carbon monoxide alarm sounds. Leave the house and call your gas utility from outside.

Parts that commonly fix it

Always match the part number to your exact model.

⚙

ECM blower motor (exact OEM match for your model)

Only after a tech confirms power and wiring are good and the motor won't respond. Communicating motors are model-specific.

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⚙

Furnace control board (exact OEM part)

Less common for code 68. Keep the original memory card with the furnace.

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⚙

Furnace air filter (your exact size)

Not a cause of code 68, but worth replacing while the blower door is open.

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Sources

  1. Rheem 92-103343-01 serial communicating gas furnace fault code label (68 = No Communications with Blower Motor; fault history shown at power-up, most recent first)
  2. Rheem (-)96V installation instructions 92-24161-124, Diagnosing Blower Motor Issues: Motor Power and Communications Issues (Fault Code 68), 115-120 VAC at pins 4 and 5 of the 5-pin connector, 24 VAC on pins 3 and 4 at P5 runs motor at 75%; one-hour lockout display; memory card must stay with the furnace
  3. Rheem 802V Series installation instructions (ManualsLib): No blower communications (68), furnace will not operate in any mode

Last reviewed 2026-10-23. Always confirm against the manual for your exact model number.