BELT SLIPPING, SQUEALING OR WORN?
A39/4L410 HVAC V-Belt — Restores Blower Speed & Airflow
41-inch outside-length, 1/2-inch wrapped drive belt with verified OEM and manufacturer cross-reference data.
A39 / 4L41041" Outside Length1/2" Top Width40° Profile
Verified Equipment Fitment: Verified Lennox model fitment: ZCB036S401. Its replacement-parts record lists Lennox 25W61 as the A39, 41-inch blower belt.
Verified Cross-Reference Information
Industry NumbersA39, 4L410
Lennox Numbers25W61, 100245-16, 25P08
Greenheck345211 (A39), 345068 (4L410)
GatesA39; PoweRated 6841 / 4L410K
Equivalent vs. Alternative Belts
Dimensional FHP EquivalentGates 6841 / 4L410K
Cogged Performance AlternativeAX39 — raw-edge cogged construction; not identical to a wrapped A39/4L410
Important: A belt can share the same nominal size while using a different cover, cord, compound or cogged construction. Match the original duty requirement as well as the section and length.
Size & Application Data
Outside Length41" / 1041 mm
Top Width1/2" / 12.7 mm
Nominal HeightApproximately 5/16" to 11/32", depending on manufacturer specification
Typical UsesHVAC blowers, rooftop units, ventilation fans, air handlers, pumps and industrial drives
Common Problems This Belt May Correct
- Startup squeal, chirp or belt slip
- Weak airflow or a blower running below normal speed
- Black belt dust around the sheaves
- A cracked, glazed, stretched, frayed or hardened belt
Check Before Ordering
- Read the complete number printed on the old belt whenever possible.
- Confirm the 1/2-inch A/4L profile and 41-inch outside-length designation.
- Inspect both sheaves for worn, widened, polished or damaged grooves.
- Check shaft alignment, bearing drag and the tensioning system.
Pro Tip: A new belt will not permanently stop noise caused by worn sheaves, misalignment or failing bearings. Correct the drive problem first, then set final tension to the equipment specification.
Installation Notes
- Disconnect and lock out electrical power.
- Release belt tension according to the service instructions.
- Do not pry the belt over a pulley; create enough slack.
- Clean and align the sheaves, then set specified tension.
- Rotate by hand, reinstall guards, restore power and test.
Frequently Asked Questions
Are A39 and 4L410 interchangeable?
They are commonly paired as the same nominal 1/2-inch, 41-inch size. Construction and duty rating can still differ by product line.
Can AX39 replace this belt?
AX39 is a related cogged performance alternative, not identical wrapped construction. Verify the equipment permits the change.
✓ Model-Specific Repair Pages
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