Navien Error Code E822: Overcooling of the air conditioning coil (Evaporator coil).
How to Fix Navien Code E822
- Step 1: Check and replace your air filter. A dirty air filter is the most common cause of restricted airflow.
- Step 2: Ensure that all supply and return air vents are open and not blocked by furniture or other obstructions.
- Step 3: After completing steps 1 and 2, reset the unit by turning it off and then back on at the breaker. If the error reappears, call a qualified HVAC technician.
How to Reset Navien Code E822
- Turn off the unit using the power button on the front panel.
- Turn off the gas supply valve.
- Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
- Restore power at the breaker, then open the gas valve.
- Turn the unit back on. If the error returns, the underlying issue needs repair.
Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.
What Does Navien Error Code E822 Mean?
The E822 error code on your Navien indicates that the evaporator coil in your air conditioning system is experiencing overcooling. This typically happens when the coil gets too cold, often leading to ice formation. This icing restricts airflow, reduces cooling efficiency, and can potentially damage the compressor if left unaddressed. The Navien system is designed to shut down to prevent further damage when this condition is detected. Think of it like your car overheating – the system is protecting itself.
Common Causes
- Refrigerant leak causing low refrigerant charge
- Restricted airflow across the evaporator coil due to a dirty air filter or blocked ductwork
- Faulty evaporator thermistor reading incorrect temperatures
- Failed or malfunctioning TXV (thermal expansion valve) causing overfeeding of refrigerant
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Evaporator coil is iced over | Measure refrigerant pressures (suction and liquid line) | Low suction pressure, potentially normal to low liquid pressure |
| Refrigerant pressures are abnormal | Check superheat and subcooling | High superheat, low subcooling indicates low charge or TXV issue |
| Airflow seems restricted | Measure static pressure across the evaporator coil | High static pressure indicates airflow restriction |
| Suspect thermistor issue | Measure resistance of the evaporator thermistor at a known temperature | Compare resistance to the thermistor's temperature/resistance chart. Deviation indicates a faulty thermistor. |
Applicable Navien Models
Source Documentation
Referenced in 1 official Navien technical manual.
| Manual | Page | Reason | Action |
|---|---|---|---|
| Navien NPF Installation & Operation Manual | 129 | Overcooling of the air conditioning coil (Evaporator coil). | This error occurs when the supply air (SA) temperature is abnormal. ● Check the status of the air conditioning coil (Evaporator coil). ● Check if the duct’s filter is clean. ● Check if the set cooling airflow is suitable for the cooling capacity. |
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Evaporator Thermistor | — | — | — |
| TXV (Thermal Expansion Valve) | — | — | — |
| Air Filter | — | — | — |
Related Codes on Same Models
Other codes that affect the same Navien model families as E822.
| Code | Description | Severity |
|---|---|---|
| E001 | Ignition Failure | Warning |
| E003 | Abnormal Ignition | Warning |
| E004 | False Flame Detection | Warning |
| E012 | Flame Loss | Warning |
| E016 | Overheating | Warning |
| E030 | Exhaust Overheat Sensor | Warning |
| E031 | Inlet Thermistor Open/Short | Warning |
| E046 | Outlet Thermistor Open/Short | Warning |
| E047 | DHW Thermistor Open/Short | Warning |
| E060 | Fan Motor Abnormality | Warning |