Ruud U802VA050317MSA Error Code *T086_F: Suction Pressure Sensor Failure (Transient, Two-Stage Only)
What Does Code *T086_F Mean?
Fault code T086_F on the Ruud U802VA is a transient, two-stage-only fault (*T086_F). It indicates that the suction pressure sensor — used by the Electronic Expansion Valve (EXV) system alongside the suction line thermistor (T085_F) for refrigerant superheat calculation — has failed or produced an out-of-range reading.
The suction pressure sensor is a transducer that converts refrigerant pressure at the compressor suction port into an electrical signal. The EXV controller uses this pressure data combined with temperature data to calculate superheat and adjust the EXV to optimize refrigerant distribution through the cooling coil. Without accurate pressure readings, the EXV cannot compute superheat and may default to a fixed opening.
Furnace heating is completely unaffected by T086_F. The T (transient) prefix confirms this was intermittent. The fault is logged in the IFC's Bluetooth diagnostic history. Because this involves the refrigerant circuit, diagnosis and replacement require a technician with refrigerant handling certification.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Faulty suction pressure sensor | Most common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- Schedule a service call with a certified HVAC technician — the suction pressure sensor is part of the refrigerant circuit
- A technician should verify the transducer connector is secure and check for refrigerant system pressures that could cause out-of-range readings
- This fault applies only to two-stage U802VA models connected to an EXV cooling system
✓ Verified against manufacturer service manual — March 2026