🌡️Heat Pump

CONTACTOR FAILURE

Lennox · XP21 Dave Lennox Signature Collection 20 SEER Heat Pump

Lennox XP21 Dave Lennox Signature Collection 20 SEER Heat Pump CONTACTOR FAILURE Error Fix: Contactor Failure

The compressor contactor (heavy-duty relay) has failed. Symptoms: unit doesn't start at all (stuck open), or runs continuously (stuck closed/welded). A buzzing contactor with unit not starting means contacts are pitted/burned. Replace contactor. Rating: 30–40 amp. Cost $10–$30 for the part.

Medium severity2 fixes available✨ Free fix available

Quick Answer

Error CONTACTOR FAILURE on the Lennox XP21 Dave Lennox Signature Collection 20 SEER Heat Pump means: Contactor Failure. The top-ranked community fix is “Replace Compressor Contactor Relay” (medium difficulty, ~45 min, DIY cost: $20-$35). 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.

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: $150-$250.

Other Lennox Models with Error CONTACTOR FAILURE

ML14XC1 Merit Series 14 SEER Single-Stage Air Conditioner

air_conditioner · 2 fixes

XC21 Dave Lennox Signature Collection 21 SEER Variable-Capacity Air Conditioner

air_conditioner · 2 fixes

XC25 Dave Lennox Signature Collection 26 SEER Variable-Capacity Air Conditioner

air_conditioner · 2 fixes

XP25 Dave Lennox Signature Collection Variable-Capacity Heat Pump

heat_pump · 2 fixes

Other Lennox XP21 Dave Lennox Signature Collection 20 SEER Heat Pump Error Codes

1 FLASH YELLOW

High Pressure Switch Open

2 fixes

2 FLASHES YELLOW

Low Pressure Switch Open

2 fixes

3 FLASHES YELLOW

Compressor Thermal Overload

2 fixes

4 FLASHES YELLOW

Short-Cycle Protection

2 fixes

ALERT 1

Communication Loss — Outdoor Unit

2 fixes

ALERT 11

High Pressure Protection — Outdoor Unit

2 fixes

ALERT 12

Low Pressure Protection — Outdoor Unit

2 fixes

ALERT 14

Compressor Discharge Temperature High

2 fixes

People Also Ask About Lennox XP21 Dave Lennox Signature Collection 20 SEER Heat Pump Error CONTACTOR FAILURE

What does error code CONTACTOR FAILURE mean on a Lennox XP21 Dave Lennox Signature Collection 20 SEER Heat Pump?

Error code CONTACTOR FAILURE on the Lennox XP21 Dave Lennox Signature Collection 20 SEER Heat Pump means: Contactor Failure. The compressor contactor (heavy-duty relay) has failed. Symptoms: unit doesn't start at all (stuck open), or runs continuously (stuck closed/welded). A buzzing contactor with unit not starting means contacts are pitted/burned. Replace contactor. Rating: 30–40 amp. Cost $10–$30 for the part.

How do I fix error code CONTACTOR FAILURE on my Lennox XP21 Dave Lennox Signature Collection 20 SEER Heat Pump?

The most successful fix is "Replace Compressor Contactor Relay" (medium difficulty, ~45 minutes). Estimated DIY cost: $20-$35. HomeMD has 2 community-ranked fixes for this error.

Is error code CONTACTOR FAILURE on a Lennox XP21 Dave Lennox Signature Collection 20 SEER Heat Pump 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 Lennox XP21 Dave Lennox Signature Collection 20 SEER Heat Pump error CONTACTOR FAILURE myself?

Yes — the top-ranked community fix ("Replace Compressor Contactor Relay") is rated medium difficulty and takes about 45 minutes. Tools needed: Phillips screwdriver, Nut driver set, Multimeter.

How much does it cost to repair Lennox XP21 Dave Lennox Signature Collection 20 SEER Heat Pump error CONTACTOR FAILURE?

DIY cost: $20-$35. Professional repair typically costs $150-$250. Many homeowners save money by trying the top-ranked community fix first.

What other error codes does the Lennox XP21 Dave Lennox Signature Collection 20 SEER Heat Pump have?

The Lennox XP21 Dave Lennox Signature Collection 20 SEER Heat Pump has 8 other known error codes, including: 1 FLASH YELLOW (High Pressure Switch Open), 2 FLASHES YELLOW (Low Pressure Switch Open), 3 FLASHES YELLOW (Compressor Thermal Overload), 4 FLASHES YELLOW (Short-Cycle Protection), ALERT 1 (Communication Loss — Outdoor Unit), and 3 more.

Which other Lennox models have the CONTACTOR FAILURE error?

Error code CONTACTOR FAILURE also appears on 4 other Lennox models: ML14XC1 Merit Series 14 SEER Single-Stage Air Conditioner, XC21 Dave Lennox Signature Collection 21 SEER Variable-Capacity Air Conditioner, XC25 Dave Lennox Signature Collection 26 SEER Variable-Capacity Air Conditioner, XP25 Dave Lennox Signature Collection Variable-Capacity Heat Pump. The fix may vary by model, so check each model's specific page for tailored repair steps.

What other error codes does the Lennox XP21 Dave Lennox Signature Collection 20 SEER Heat Pump have?

The Lennox XP21 Dave Lennox Signature Collection 20 SEER Heat Pump has 8 other known error codes:

1 FLASH YELLOW — High Pressure Switch Open (2 fixes)
2 FLASHES YELLOW — Low Pressure Switch Open (2 fixes)
3 FLASHES YELLOW — Compressor Thermal Overload (2 fixes)
4 FLASHES YELLOW — Short-Cycle Protection (2 fixes)
ALERT 1 — Communication Loss — Outdoor Unit (2 fixes)
ALERT 11 — High Pressure Protection — Outdoor Unit (2 fixes)
ALERT 12 — Low Pressure Protection — Outdoor Unit (2 fixes)
ALERT 14 — Compressor Discharge Temperature High (2 fixes)

Which other Lennox models have the CONTACTOR FAILURE error?

Error code CONTACTOR FAILURE also appears on 4 other Lennox models:

ML14XC1 Merit Series 14 SEER Single-Stage Air Conditioner (air conditioner) · 2 fixes
XC21 Dave Lennox Signature Collection 21 SEER Variable-Capacity Air Conditioner (air conditioner) · 2 fixes
XC25 Dave Lennox Signature Collection 26 SEER Variable-Capacity Air Conditioner (air conditioner) · 2 fixes
XP25 Dave Lennox Signature Collection Variable-Capacity Heat Pump (heat pump) · 2 fixes

Ad Space — banner

Replace ADSENSE_PUBLISHER_ID in AdUnit.tsx