E1
York · YZH36B21S 3 Ton 16 SEER 9.5 HSPF Heat Pump with Environmentally Friendly Refrigerant
The indoor coil temperature sensor has failed or is giving inaccurate readings. This causes improper defrost cycles or heating performance issues.
Error E1 on the York YZH36B21S 3 Ton 16 SEER 9.5 HSPF Heat Pump with Environmentally Friendly Refrigerant means: Indoor Coil Temperature Sensor Fault. The top-ranked community fix is “Replace Indoor Coil Temperature Sensor” (medium difficulty, ~40 min, DIY cost: $30-$50). 2 community-ranked fixes available below.
Published February 2026 · 2 fixes · heat pump
Content is based on manufacturer service documentation, community repair experience, and OEM technical bulletins. Always verify with your owner's manual.Learn about our editorial standards.
While many heat pump repairs can be done safely at home, consider hiring a qualified technician if:
Average professional repair cost for this issue: $130-$200.
Outdoor Ambient Sensor Fault
Communication Fault Between Indoor and Outdoor Units
Indoor Coil Freeze Protection Sensor Fault
Compressor Start Relay Fault
Outdoor Coil Freeze Protection Sensor Fault
Indoor Unit Communication Fault
Outdoor Unit Communication Fault
Indoor Unit EEPROM Fault
The York YZH36B21S 3 Ton 16 SEER 9.5 HSPF Heat Pump with Environmentally Friendly Refrigerant has 8 other known error codes:
Error code E1 also appears on 3 other York models:
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