E5 Outdoor control low-voltage fuse open

What the control is telling you

The 24 V fuse on the outdoor control has blown, so the A/C or heat pump does not run.

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

• Short to ground or between conductors in the low-voltage wiring

Test and repair steps

1. Warning: Kill power to the outdoor unit before touching wiring, the compressor terminals or the control.
2. Find the short first check thermostat/communication wires for nicks, pinches against sheet metal, and wiring at the contactor coil, reversing valve and pressure switches.
3. Replace the fuse only with a 3 A automotive (blade) fuse.
4. Restore power and confirm the code clears; if the fuse blows again, isolate circuits one at a time until the short is found.

Models that show this code

24 models in Goodman/Amana ComfortNet ASZC/GSZC/DSZC

Other codes on the same units

• d1 Invalid shared data on the network
• 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
• H8 High line voltage
• L1 Lockout - low pressure switch tripped 3 times
• L2 Lockout - high pressure switch tripped 3 times
• L6 Lockout - open start circuit detected 4 times