3 Flashes Draft pressure error

What the control is telling you

Draft pressure is out of range. Check the venting, pressure switch and inducer.

Applies to: Integrated furnace control

Likely causes

• Venting problem
• Pressure switch problem
• Inducer problem

Test and repair steps

1. Check venting for blockage or restriction.
2. Check the pressure switch.
3. Check the inducer.

Settings for these units

• Clearance to combustibles · Trane S8V2
• Return filter size by cabinet width · Trane S8V2
• Return filter size by cabinet width · Trane S8B1, Trane S8X1, Trane S8X2
• Return filter size - upflow and downflow · Trane S9X1, Trane S9X2, Trane S9B1
• Clearance to combustibles · Trane S9X1, Trane S9X2, Trane S9B1
• Return filter size - upflow and downflow · Trane S9V2

Other codes on the same units

• 2 Flashes System lockout
• 4 Flashes Open high limit device
• 5 Flashes Flame sensed with no flame expected
• 6 Flashes 115 V AC power reversed or poor grounding
• 7 Flashes Gas valve circuit error
• 8 Flashes Low flame sense signal
• 9 Flashes Ignitor circuit or neutral-to-common voltage
• Continuous OFF Check power

Sequence of operation

What the unit does around this code, step by step.

• Heating sequence of operation · Heating