HVACopediaKeepRite · Furnace · Other
Furnace used with a heat pump (dual fuel blower timing)
What happens, in order
- Control sees R-W with Y1 (or Y/Y2) and changes its blower timing so the duct air does not go cold during heat pump defrost
- Blower is brought on at the matching cooling or heat speed and stays on through prepurge, then shuts off 24 s (25 s on 9MAE after burners light) and comes back at heat speed
- W drops normal inducer post-purge runs; the blower follows any Y signal still present (cool speed with Y/Y2, low-cool with Y1); on the two-stage furnace it switches to cool speed after a 3 s delay
- If W, Y and G all drop together the blower runs the selected off-delay; if G stays on, the blower then moves to continuous fan speed
Timings and thresholds
| Item | Value |
|---|---|
| Blower dropout in heat cycle | 24 s (9MXE, 9MXT); 25 s (9MAE) |
| Speed change after W drops (two-stage) | 3 s |
Applies to: KeepRite / ICP (F-G)9MXE single-stage 95% furnace (KeepRite G9MXE); KeepRite / ICP (F-G)9MXT two-stage 95% furnace (KeepRite G9MXT); ICP (F-G)9MAE modulating 95% furnace
Models
More KeepRite furnace sequences
- Modulating 95% furnace: ignition sequence and retries · Ignition
- Single- and two-stage 95% furnace: ignition sequence and retries · Ignition
- Modulating 95% furnace: adaptive heating, staging and blower delays · Heating
- Single-stage 95% furnace: heating cycle and blower delays · Heating
- Two-stage 95% furnace: low/high heat, staging and blower delays · Heating
- Furnace blower with outdoor A/C: cooling, dehumidify and continuous fan · Cooling
Take it to the job
Sequences of operation, error codes and tips work offline in the HVACopedia app.
Source: KeepRite/ICP (F-G)9MXE service manual 440 04 4311 09, Sequence of Operation / KeepRite/ICP (F-G)9MXT service manual 440 04 4321 10, Sequence of Operation / ICP (F-G)9MAE service manual 440 04 4700 00, 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.