Purpose:
This article uses generic diagram and electric panel layouts to illustrate how the multi-speed fan functions. This may be used to help verify wiring and component issues in the field in the event the supply fan isn't functioning properly.
Resolution:
Notice: The screen shots contained in this article are generic. See your unit electric diagram for specific wiring.
There are two different overloads for high (HS/OL) and low speed (LS/OL) fan which are manual reset. See the motor starter locations below for location information and verify the overload isn't tripped.
Fan speed control is accomplished using motor starters which jump together different motor leads to stage the fan from Low to High speed.
The fan runs at high speed when you have set to run at high-speed using a zone sensor or via BAS, a compressor is operating, or if refrigerant leak has been detected.
There are multiple ways to command the fan speed manually.
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WARNING:
Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.