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York · YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor

York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor E3 Error Fix: Defrost Sensor Fault

This error signifies that the defrost sensor is malfunctioning or reading abnormal temperatures, preventing the heat pump from entering proper defrost cycles. This can cause ice buildup on the outdoor coil and reduced heating efficiency.

Medium severity2 fixes available

Quick Answer

Error E3 on the York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor means: Defrost Sensor Fault. The top-ranked community fix is “Replace defrost temperature sensor” (medium difficulty, ~40 min, DIY cost: $35-$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.

Root Cause Analysis

Sensor MalfunctionPrimary

When to Call a Professional

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

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-$200.

Other York Models with Error E3

DERA-F036N07 14 SEER

air_conditioner · 2 fixes

YZF42B21S LX Series AC

air_conditioner · 2 fixes

YZH36B21S 3 Ton 16 SEER 9.5 HSPF Heat Pump with Environmentally Friendly Refrigerant

heat_pump · 2 fixes

Other York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor Error Codes

High Pressure Switch Trip

2 fixes

E10

Indoor Coil Freeze Warning

2 fixes

E11

Compressor Start Relay Failure

2 fixes

E12

Communication Error Between Indoor and Outdoor Units

2 fixes

E13

Outdoor Ambient Temperature Sensor Failure

2 fixes

E14

High Limit Thermostat Open

2 fixes

E15

Freeze Protection Sensor Open

2 fixes

E16

Drain Pump Failure

2 fixes

People Also Ask About York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor Error E3

What does error code E3 mean on a York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor?

Error code E3 on the York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor means: Defrost Sensor Fault. This error signifies that the defrost sensor is malfunctioning or reading abnormal temperatures, preventing the heat pump from entering proper defrost cycles. This can cause ice buildup on the outdoor coil and reduced heating efficiency.

How do I fix error code E3 on my York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor?

The most successful fix is "Replace defrost temperature sensor" (medium difficulty, ~40 minutes). Estimated DIY cost: $35-$50. HomeMD has 2 community-ranked fixes for this error.

Is error code E3 on a York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor serious?

This error is rated medium severity. It should be addressed soon, but your appliance may still function in a limited capacity.

Can I fix York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor error E3 myself?

Yes — the top-ranked community fix ("Replace defrost temperature sensor") is rated medium difficulty and takes about 40 minutes. Tools needed: Phillips screwdriver, Multimeter.

How much does it cost to repair York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor error E3?

DIY cost: $35-$50. Professional repair typically costs $130-$200. Many homeowners save money by trying the top-ranked community fix first.

What other error codes does the York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor have?

The York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor has 8 other known error codes, including: E1 (High Pressure Switch Trip), E10 (Indoor Coil Freeze Warning), E11 (Compressor Start Relay Failure), E12 (Communication Error Between Indoor and Outdoor Units), E13 (Outdoor Ambient Temperature Sensor Failure), and 3 more.

Which other York models have the E3 error?

Error code E3 also appears on 3 other York models: DERA-F036N07 14 SEER, YZF42B21S LX Series AC, YZH36B21S 3 Ton 16 SEER 9.5 HSPF Heat Pump with Environmentally Friendly Refrigerant. The fix may vary by model, so check each model's specific page for tailored repair steps.

What other error codes does the York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor have?

The York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor has 8 other known error codes:

E1 — High Pressure Switch Trip (2 fixes)
E10 — Indoor Coil Freeze Warning (2 fixes)
E11 — Compressor Start Relay Failure (2 fixes)
E12 — Communication Error Between Indoor and Outdoor Units (2 fixes)
E13 — Outdoor Ambient Temperature Sensor Failure (2 fixes)
E14 — High Limit Thermostat Open (2 fixes)
E15 — Freeze Protection Sensor Open (2 fixes)
E16 — Drain Pump Failure (2 fixes)

Which other York models have the E3 error?

Error code E3 also appears on 3 other York models:

DERA-F036N07 14 SEER (air conditioner) · 2 fixes
YZF42B21S LX Series AC (air conditioner) · 2 fixes
YZH36B21S 3 Ton 16 SEER 9.5 HSPF Heat Pump with Environmentally Friendly Refrigerant (heat pump) · 2 fixes

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