What It Means
Compressor motor is running but failing to pump refrigerant.
Bryant Heat Pump
Bryant Heat Pump Error Code 79
Troubleshooting guide for the Bryant Heat Pump system fault 79.
Possible Causes
- Severe refrigerant loss or undercharge.
- Refrigerant line restriction, kink, or plugged filter drier.
- Flooded start condition during cold ambient off-cycle.
- Internal mechanical failure in compressor pump mechanism.
Not sure which one it is — or if it's none of these? Try ACLogics today.
Disclaimer: This information is for general reference. Error codes can vary by model and production year. Always refer to your machine's specific manual and the information printed on the unit itself.
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Full Diagnosis
Compressor No-Pump Event. The board detects that the compressor is running and drawing current but is not actually moving refrigerant through the circuit, so it shuts the compressor down for the retry interval rather than let it run without lubrication or cooling flow. This differs from code 62 (compressor no-start), where the compressor never gets going at all — in a no-pump event the compressor is confirmed running electrically but failing mechanically or refrigerant-wise to do its job, pointing at flooded start, a blocked suction line, or an internal mechanical failure rather than a wiring or contactor problem. It also differs from codes 72 (suction over-temp) and 32 (low-pressure trip), which are triggered by sensor/pressure readings on a compressor that is pumping normally; a no-pump event instead catches a compressor that looks electrically fine but isn't doing mechanical work. Board retries after 5 minutes, the same interval used for compressor motor over-temperature (code 71), giving refrigerant migration or a flooded condition time to settle before the next attempt.
All Recorded Causes
Check refrigerant charge level — an undercharged system can starve the compressor of enough refrigerant flow to look like a no-pump condition. Inspect for a refrigerant system blockage (restricted metering device, crimped line, plugged filter drier) that would prevent flow even with a healthy compressor. Verify compressor suction and discharge pressures during a run attempt to see whether the compressor is developing a normal pressure differential. Check for a flooded compressor start condition, particularly after a long off-cycle in cold weather, which can temporarily prevent normal pumping. Inspect inverter drive output waveform if this is an inverter-driven compressor. Board retries after 5 minutes; a compressor that repeatedly no-pumps after charge and blockage are ruled out likely has an internal mechanical failure.
Verify Before Replacing Parts
- Confirm the exact Bryant model family and heat pumps context before acting on a generic code description.
- Confirm board LEDs, wiring polarity, and model compatibility before replacing control boards — this Bryant fault points at check refrigerant charge level — an undercharged system can starve the compressor of enoug….
- Check for intermittent communication faults caused by connectors, moisture, or damaged harnesses, and rule out inspect for a refrigerant system blockage (restricted metering device, crimped line, plugg….
- After the correction, run the system long enough to confirm the heat pumps fault does not return under normal load.
Still unsure about this fault?
ACLogics walks you through Bryant Heat Pump diagnostics step-by-step — so you confirm the cause before swapping parts.
