HVACopediaGoodman-Amana-Daikin · Furnace · Ignition
Gas heat call and shutdown
What happens, in order
- 115 V on: control runs internal checks and its LED lights; it monitors safety circuits all the time
- R and W thermostat contacts close
- Control checks the safety circuits
- Inducer starts and the pressure switch closes; inducer keeps running for the pre-purge
- Igniter warms up after pre-purge
- Gas valve opens at the end of igniter warm-up
- Control looks for flame within 4 s of the valve opening; gas continues only with a flame signal
- Circulator blower starts on heat speed after the fixed 30 s on delay
- Thermostat opens gas valve closes
- Inducer runs a 15 s post-purge
- Circulator blower runs the selected off delay then stops
- Failed ignition 3 retries in one call then lockout (E0)
Timings and thresholds
| Item | Value |
|---|---|
| Trial for flame check | 4 s |
| Blower on delay | 30 s |
| Post-purge | 15 s |
| Blower off delay | 90, 120, 150 or 180 s |
| Ignition retries | 3 total, then lockout |
Codes you may see during this
Applies to: Goodman GM9S80, GC9S80; Amana AM9S80, AC9S80
Models
More Goodman-Amana-Daikin furnace sequences
- Gas heat call, first and second stage · Ignition
- Two-stage gas heat call with ramped blower · Heating
- Cooling and fan only · Cooling
- Cooling and fan only · Cooling
- Low and second stage cooling with the furnace blower · Cooling
Take it to the job
Sequences of operation, error codes and tips work offline in the HVACopedia app.
Source: Goodman GM9S80 / AM9S80 / GC9S80 / AC9S80 service RS6621008r2, Normal Sequence of Operation. Written in our own words; timings can differ by model and software version, so check the manual for your exact unit.
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.