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Noisy registers, drafts, blower overamps/ECM noise, coil freezing

What is going on

Possible causes and checks for: noisy registers, drafts, blower overamps/ecm noise, coil freezing.

Likely causes

  • Too few zones open without bypass
  • Airflow below
  • Cfm/ton

Check in this order

  1. Barometric or motorized bypass damper, freezestat, weight adjustment on barometric arm. pp.994–998 [968–972]

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Source: General HVAC service practice — verify per model. Written in our own words; check the manual for your exact model.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.