Two-stage gas heat call with ramped blower

What happens, in order

1. R and W1 (or W1 and W2) close
2. Control checks safety circuits
3. Inducer runs on high speed for a 15 s pre-purge; humidifier terminal is energized with it
4. Inducer steps down to low speed and the low-stage pressure switch must be closed
5. Igniter warm-up starts once low speed and the closed switch are confirmed
6. Gas valve opens at the end of the warm-up and flame is established; valve stays open only with flame
7. Low heat call valve and inducer stay low; high heat call: they step to high stage
8. Circulator blower starts on heat speed after a 30 s on delay and takes 30 s to reach full speed; air cleaner terminal energized with it
9. Low to high call inducer, valve and blower switch to high right away
10. High to low call inducer and valve drop to low at once; blower holds high speed for 30 s then goes to low heat speed
11. Call ends valve closes, inducer runs a 15 s post-purge, humidifier output off
12. Blower runs out the heat off delay; after a high-heat call it runs high speed 30 s and then low speed for the rest of the delay
13. Blower and air cleaner turn off, blower ramps down over the next 30 s
14. Three failed ignition attempts in one call lock the furnace out with E0; it resets itself after 1 hour, or on a power interruption, or by dropping the thermostat call for 1 to 20 s

Timings and thresholds

Codes you may see during this

E0

Models

More Goodman-Amana-Daikin furnace sequences

• Gas heat call and shutdown · Ignition
• Gas heat call, first and second stage · Ignition
• Cooling and fan only · Cooling
• Cooling and fan only · Cooling
• Low and second stage cooling with the furnace blower · Cooling