HVACopediaGoodman · Heat pump
H8 High line voltage
What the control is telling you
Line voltage measured above 255 VAC. Clears when voltage drops back below 255 VAC.
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
- Supply voltage too high
Test and repair steps
- Warning: Kill power to the outdoor unit before touching wiring, the compressor terminals or the control.
- Measure line voltage at the unit.
- Confirm the unit is on the supply voltage shown on the rating plate.
- Have the utility correct a high supply voltage.
Models that show this code
24 models in Goodman/Amana ComfortNet ASZC/GSZC/DSZC
Other codes on the same units
- d2 System mismatch - indoor unit cannot supply required airflow
- d3 Configuration mismatch - shared data does not match hardware
- d4 Shared data from the loader rejected
- E5 Outdoor control low-voltage fuse open
- L1 Lockout - low pressure switch tripped 3 times
- L2 Lockout - high pressure switch tripped 3 times
- L6 Lockout - open start circuit detected 4 times
- L7 Lockout - open run circuit detected 4 times
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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.