A030_A - Open Fuse
Status
This is a critical alarm, the unit will not operate in any mode.
Description
The fuse has been opened. This usually occurs when there is a 24VAC short to common or ground on the low voltage side of the transformer.
Expected Operation
Aconductive fuse is always expected be present for normal operation. If however, thefuse is sensed open, the Air Handler Control will:
- Ignore all requests. Possible operation in progress finishes in the same way as if the request was removed.
- Alarm “A030_A Open Fuse” is declared.
- During the time the fuse is sensed open, treats the rollout limit switch, main limit switch, heat assisted limit control and both auxiliary inputs as closed to assure correct reaction on the open fuse condition (otherwise the switches would be falsely sensed open).
Once thefuse is sensed conductive again, the Air Handler Control shall revert back to normaloperation and the alarm will be cleared.
Cause
An electrical short from low voltage (24VAC) to ground or common has occurred.
Solution
Technician should replace the fuse on Air Handler control.
If problem persists, Replace Air Handler control.
