Ruud U802VA050317MSA Error Code *A055_F: Inducer Hi Pressure Switch Won't Open (Active, Two-Stage Only)
What Does Code *A055_F Mean?
Fault code A055_F on the Ruud U802VA is an active fault that applies only to two-stage models (*A055_F). It is the persistent counterpart to T055_F — while T055_F indicates an intermittent condition, A055_F indicates the high-stage pressure switch is consistently stuck in the closed position when the IFC expects it to be open.
The A (active) prefix means this is an ongoing condition rather than a transient one. The IFC has confirmed this is not an intermittent reading — the high-stage switch is persistently closed when it should be open. Because the furnace control will not initiate a heat cycle during any lockout condition, high-stage heating is unavailable until this fault is resolved.
Power cycling can clear the lockout attempt, but the switch itself must be repaired or replaced before the fault will stop recurring. A mechanical failure inside the high-stage pressure switch is the most likely cause at this point, since a transient cause (moisture, wind) would likely produce T055_F rather than the persistent A055_F fault code.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Failed high-stage pressure switch | Most common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- Any time this code appears — the high-stage pressure switch needs replacement by a qualified HVAC technician on your two-stage U802VA
- Power cycling will temporarily clear the lockout but will not fix the underlying stuck switch
- A technician should confirm the correct high-stage switch part number for this specific two-stage U802VA model before replacement
✓ Verified against manufacturer service manual — March 2026