Rheem Error Code P1: Rheem Code P1 - Defrost Error
Warning: Your Rheem heat pump has detected a defrost error and has likely locked out to prevent damage. This means your heat pump is no longer heating efficiently and needs attention.
How to Fix Rheem Code P1
- Step 1: Check the outdoor unit for any obstructions like snow, ice, leaves, or debris blocking airflow. Clear away anything restricting the coil.
- Step 2: Ensure the area around the outdoor unit is clear to allow for proper ventilation.
- Step 3: If the issue persists after clearing any obstructions, contact a qualified HVAC technician to diagnose and repair the problem.
How to Reset Rheem Code P1
- 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 Rheem Error Code P1 Mean?
The P1 error code on your Rheem heat pump indicates a problem during the defrost cycle. Heat pumps move heat from outside to inside your home. When it's cold outside, frost can build up on the outdoor coil, reducing its ability to absorb heat. To combat this, the heat pump periodically goes into 'defrost' mode to melt the ice. The P1 error means the system isn't defrosting correctly, potentially due to a faulty sensor, a problem with the reversing valve, or airflow issues. Ignoring this can lead to the heat pump completely freezing up, causing further damage and leaving you without heat.
Common Causes
- Faulty defrost sensor (thermistor) reading incorrect temperatures.
- Refrigerant leak causing low pressure and inefficient defrosting.
- Failed reversing valve preventing the system from switching to defrost mode.
- Frozen outdoor coil due to poor airflow (blocked by snow, ice, or debris).
- Defective control board not initiating or completing the defrost cycle.
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Outdoor coil is heavily iced over | Measure the resistance of the defrost sensor (thermistor) at the outdoor coil. | Compare the reading to the temperature/resistance chart in the Rheem service manual. An open or shorted sensor indicates a fault. |
| Defrost sensor checks out | Check the voltage to the reversing valve solenoid during a defrost cycle. | Typically 24VAC. No voltage indicates a control board or wiring issue. |
| Reversing valve voltage is present | Measure the refrigerant pressures with gauges. | Pressures should be within the normal operating range specified on the unit's data plate. Low pressure indicates a refrigerant leak. |
| Pressures are normal, and reversing valve is energized | Inspect the reversing valve for proper operation. Use a temperature probe to check the temperature of the lines entering and exiting the valve during defrost. | A significant temperature difference indicates the valve is not switching properly. |
Applicable Rheem Models
- NCB(gas)
- NPE(electric)
- R801T(gas)
- R92E(electric)
- R92V(gas)
- RGE(gas)
- RH2T(electric)
- RNC(dual_fuel)
- RNE(electric)
- RNG(gas)
- RP16(electric)
- RPB(gas)
- RTGH(gas)
- Rheem Classic(gas)
- Rheem Classic 80 Plus(gas)
- Rheem Classic 80% Gas Furnace(gas)
- Rheem Classic 90 Plus(gas)
- Rheem Classic Plus Series(gas)
- Rheem Classic Series(dual_fuel)
- Rheem Prestige(gas)
- Rheem Prestige 95% Gas Furnace(gas)
- Rheem Prestige Series(gas)
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Defrost Sensor (Thermistor) | — | — | — |
| Reversing Valve | — | — | — |
| Control Board | — | — | — |
Related Codes on Same Models
Other codes that affect the same Rheem model families as P1.
| Code | Description | Severity |
|---|---|---|
| A001 | Ignition Failure | Warning |
| A021 | Over-Temperature | Warning |
| A031 | Inlet Thermistor Open/Short | Warning |
| A041 | Outlet Thermistor Open/Short | Warning |
| A043 | Water Level Error | Warning |
| A051 | Fan Motor Abnormality | Warning |
| A052 | Fan Motor Speed Error | Warning |
| A053 | Fan Motor Open Circuit | Warning |
| A054 | Fan Motor Overcurrent | Warning |
| A055 | Fan Motor Locked | Warning |