HVACopediaGoodman · Heat pump
d2 System mismatch - indoor unit cannot supply required airflow
What the control is telling you
In a communicating system the outdoor unit needs more airflow than the indoor unit can deliver, or the shared data is incompatible / missing values. The unit may not run, or runs at reduced capacity or on low stage only.
Applies to: Communicating 2-stage condensers and heat pumps with the PCBHR104 or PCBHR105 outdoor control (7-segment display): ASXC16/18, GSXC16/18, DSXC16/18, ASZC16/18, GSZC16/18, DSZC16/18
Likely causes
- Indoor unit too small for the outdoor unit
- Shared data not compatible with the system or missing parameters
Test and repair steps
- Warning: Kill power to the outdoor unit before touching wiring, the compressor terminals or the control.
- Check model numbers of both units against the approved match-ups.
- Verify the shared data matches the exact model; reload it with the BTSDL01 if needed.
- Plug the BTSDL01 in BEFORE turning power on; after the data loads, turn power off before unplugging it.
- If the system cannot be run as communicating, wire it as a legacy 24 V system instead.
Models that show this code
24 models in Goodman/Amana ComfortNet ASZC/GSZC/DSZC
Other codes on the same units
- b0 Indoor blower not running when it should be
- b9 Indoor airflow lower than requested
- d0 No shared data on the network
- d1 Invalid shared data on the network
- d3 Configuration mismatch - shared data does not match hardware
- d4 Shared data from the loader rejected
- E5 Outdoor control low-voltage fuse open
- H8 High line voltage
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Source: Goodman ComfortNet ASXC/GSXC/DSXC, ASZC/GSZC/DSZC, AVPTC/MBVC service manual, Unitary Diagnostic Codes PCBHR104 p.71-77 and PCBHR105 p.78-84. Summarized in our own words; check the original manual for your model.
Homeowner looking at this code? See what it means for you and when to call a technician.
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.