HVACopediaGoodman-Amana-Daikin · Heat pump · Defrost
Communicating defrost and forced defrost
What happens, in order
- Heat pump runs in heating
- Coil temperature below about 31 F UC board accumulates compressor run time
- When run time reaches the dip-switch interval and heat is called, defrost starts
- UC control turns the condenser fan off and energizes the reversing valve; compressor may pause briefly during the valve shift (delay is adjustable)
- Compressor restarts at high stage
- Air handler is asked to run the electric heat and blower at defrost speed
- Defrost ends at about 75 F coil temperature or after 10 min maximum, whichever comes first; timer resets
- System goes back to the heating mode it was in
- Service test press TEST and RECALL together on the UC board to force defrost
Timings and thresholds
| Item | Value |
|---|---|
| Defrost interval (dip switch) | 30, 60, 90 or 120 min |
| Start sensing temperature | about 31 F |
| End temperature | about 75 F |
| Max defrost time | 10 min |
Applies to: Goodman ComfortNet ASZC / GSZC / DSZC heat pumps
Models
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Source: Goodman ComfortNet ASXC/DSXC/GSXC service, Defrost Cycle - Communicating Models; Sequence of Operation 3.0. 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.