HVACopediaCarrier · Furnace · Other
Furnace used with a heat pump (dual fuel timing)
What happens, in order
- Control detects R-W with Y (or Y and G) and changes its blower timing to avoid long blower-off periods during heat pump defrost
- Blower stays on at heat speed through the prepurge, drops out for 24 s, then comes back on at heat speed
- W drops normal inducer post-purge runs and the blower moves to cool speed after a 3 s delay
- If W, Y and G all drop together the blower runs for the selected blower-off delay
- If W and Y drop but G stays, blower runs the blower-off delay at heat speed and then holds
Timings and thresholds
| Item | Value |
|---|---|
| Blower dropout in heat cycle | 24 s |
| Speed change delay after W drops | 3 s |
Applies to: Carrier 58SB0A / 58SB1A 80% single-stage gas furnace
Models
58SB0A58SB1A
More Carrier furnace sequences
Related
Take it to the job
Sequences of operation, error codes and tips work offline in the HVACopedia app.
Source: Carrier 58SB0A/58SB1A installation manual, 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.