T055_F: Inducer Hi Pressure Switch Won't Open
Status
This fault limits gas heating. The furnace will operate in gas heating mode but will only run at low stage. This fault occurs in 80+ furnaces only.
Description
The high pressure switch should not be closed when the inducer is not running. The switch may be welded closed or purposely bypassed in the field. Before any heat cycle begins, the pressure switch is tested to make sure that it is opened. The switch is ignored except in gas heating modes.
Expected Operation
If the high pressure switch is stuck closed when it should be open but the low pressure switch is open as expected, the furnace control will proceed with the heat cycle in low stage while setting alert “T055_F Inducer Hi Pressure Switch Won't Open”. This alert will remain declared until the heat call is removed.
Cause
1. Faulty Switch
2. Pressure switch physically bypassed in the field.
3. Loose or faulty wiring.
4. Abnormally high negative pressure present on vent system without inducer running.
Solution
1. Replace high pressure control (switch).
2. Remove bypass and restore correct operation. Determine reason for bypass (e.g. vent length too long) and correct issue. Notify homeowner and proper authorities of illegal tampering if necessary.
3. Check wiring and connections. Replace and/or repair as necessary.
4. Check for proper venting and terminations as defined in the furnace installation instructions.
