BELT SLIPPING, SQUEALING OR WORN?
A35/4L370 HVAC V-Belt — Restores Blower Speed & Airflow
Wrapped A-section / 4L drive belt for compatible HVAC blowers, fans, pumps and equipment drives.
A35 / 4L37037" Outside Length1/2" Top Width40° Profile
Fitment rule: No manufacturer-published model-level list was verified. Match the complete A35/4L370 marking, 1/2-inch profile and 37-inch outside length—not equipment type alone.
Verified Cross-Reference Information
Industry NumbersA35, 4L370
Lennox / Browning25P04
Greenheck345064 / 4L370
Dimensional FHP EquivalentGates 6837 / 4L370K
Important: The Gates FHP number is a dimensional equivalent. Cover, cord and duty construction can differ from a wrapped classical belt.
Size & Application Data
Outside Length37" / 940 mm
Top Width1/2" / 12.7 mm
Nominal HeightApproximately 5/16" to 11/32", depending on product line
IncludedOne new wrapped drive belt
Common Problems This Belt May Correct
- Startup squeal, chirp or belt slip
- Weak airflow or a fan, blower or pump running slowly
- Black belt dust around the sheaves
- A cracked, glazed, stretched or frayed belt
Check Before Ordering
- Read the complete number printed on the old belt.
- Confirm the 1/2-inch A/4L profile and 37-inch outside length.
- Inspect sheaves for worn or widened grooves.
- Check alignment, bearing drag and belt tension.
Pro Tip: Correct worn sheaves, misalignment or failing bearings before installing the new belt.
Installation Notes
- Disconnect and lock out power.
- Release tension according to the service manual.
- Do not pry the belt over a pulley.
- Align sheaves and set specified tension.
- Rotate by hand, reinstall guards and test.
Frequently Asked Questions
Are A35 and 4L370 the same nominal size?
They are commonly dual-designated for this 1/2-inch, 37-inch outside-length size. Construction can still differ by product line.
✓ Model-Specific Repair Pages
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