York YZH36B21S 3 Ton 16 SEER 9.5 HSPF Heat Pump with Environmentally Friendly Refrigerant E4 Error Fix: Defrost Sensor Fault

When to Call a Professional

While many heat pump repairs can be done safely at home, consider hiring a qualified technician if:

• This is a high severity error — continued use may cause damage or a safety hazard
• The repair involves electrical wiring, gas lines, or refrigerant
• You've tried the top-ranked fix and the error persists
• You smell gas, see sparking, or notice water leaking
• The repair requires specialized tools you don't have
• Your appliance is still under manufacturer warranty

Average professional repair cost for this issue: $130-$190.