HVACopediaGoodman · Air handler
RDS 4 flashes R32 sensor internal fault
What the control is telling you
Red LED flashes 4 times, then off 5 s: communication with the sensor is fine but the sensor reports an internal fault.
Applies to: R-32 air handlers with refrigerant detection system (A2L PCB + R32 sensor): AMST, AWSF/AWST, ACSF
Likely causes
- Failed R32 sensor
Test and repair steps
- Unplug and reconnect the R32 sensor, then power cycle.
- If normal or delay mode returns, no further action.
- If 4 flashes remain, replace the sensor (use only the manufacturer-specified sensor).
Models that show this code
4 models in Goodman/Amana R-32 AMST/AWSF/ACSF air handlers
Other codes on the same units
- RDS 2 flashes Control board internal fault (leak detection board)
- RDS 3 flashes R32 sensor communication fault
- RDS fast flash R-32 leak alarm (or system verification test)
- RDS steady on Delay mode after leak alarm or fault
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Source: Goodman RS6200301 R-32 GLXS/ALXS/GLZS/ALZS service (07-2024), A2L PCB Fault Code and Recommended Action table p.25-26. Summarized in our own words; check the original manual for your model.
Homeowner looking at this code? See what it means for you and when to call a technician.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.