49L89 Lennox L150-30F 3" limit switch

Limit control switch. L150F-30. Back plate measures 1-7/8" x 3-1/8" with two 1/4" spade terminals. 3" arm length. Switch opens at 150F, resets at 120F. 49L8901.

The Lennox 49L89 is a genuine OEM L150-30F high-limit switch used in Lennox forced-air furnaces. This safety switch opens at 150°F and automatically resets after the temperature drops by 30°F, protecting the heat exchanger from overheating due to airflow restrictions, dirty filters, blower failure, or duct blockage.

This 3-inch insertion-depth limit switch is engineered to Lennox specifications for precise temperature response, reliable burner shutdown, and safe automatic reset. Using the OEM switch maintains furnace safety certifications and proper cycling behavior.

Grounded product data:

• OEM, opens at 150°F, 30°F differential, automatic reset, and furnace overheating protection.

• Technical Hot & Cold confirms OEM replacement, 3" limit, and compatibility with Lennox, Allied, Armstrong, Concord, Ducane, Magic Chef, and Magic-Pak models.

Cross-Reference

Direct OEM

• 49L89 — Lennox L150-30F Limit Switch (3")

Replaces / Interchange

• 49L8901 (older Lennox number)

Compatible Furnace Families

(Confirmed across Parts Town & Technical Hot & Cold)

• Lennox G60DFV series

• Lennox KGA092 / KGA102 / KGA120 / KGA150 series

• Lennox LGH092 / LGH102 / LGH120 / LGH150 / LGH152 series

• Allied, Armstrong, Concord, Ducane, Magic Chef, Magic-Pak equivalents

Technician Notes

• Trip Temperature: 150°F

• Differential: 30°F (auto-reset at ~120°F)

• Length: 3" insertion depth

• Circuit: SPST, normally closed (opens on temperature rise)

• Function: Protects heat exchanger from overheating

• Common Symptoms:

  • Furnace starts then shuts down (limit opening)

  • Blower runs continuously while burners stay off

  • Short-cycling

• Do NOT up-rate the limit switch — using a higher temperature limit is unsafe and can damage the heat exchanger.

• Always diagnose airflow issues first: dirty filter, blower failure, blocked return, closed registers.