45 Low pressure switch open - inducer high speed

What the control is telling you

Low pressure switch did not close (or opened) with the inducer on high speed. If not closed after 60 seconds of inducer run, a 5-minute soft lockout follows. RGPE/RGLE: Table 16 text LPC OPEN; meaning per 802P - verify on unit. Not stored back-to-back in the RGPE fault buffer.

Applies to: 802P/80MDP (802PA050-150); RGPE/RGLE 2-stage 80+

Likely causes

• Inducer not running or weak
• Loose, leaking, kinked or water-filled pressure hose
• Blocked vent, improper vent size/length or too many elbows
• Wind / severe downdraft
• 802P: leaky inducer gasket
• Faulty switch or wiring

Test and repair steps

1. Check the inducer runs, its line voltage and wiring (RGPE/RGLE: J2 pin 1 to pin 4 for high output; check inducer capacitor).
2. Check pressure switch hoses for cracks, kinks or water.
3. Check vent and intake for blockage, too many elbows or excessive length; check for wind/downdraft.
4. 802P check inducer gasket.
5. Check switch wiring and contacts; verify switch state with a meter while the inducer runs.

Settings for these units

• Filter sizes as shipped, upflow (Table 19) · RGPE/RGLE
• Reduced clearance to combustibles, upflow/horizontal (Fig. 4) · Rheem/Ruud 802P / 80MDP 80% two-stage furnace (UT 1028-928 IFC)
• Reduced clearance to combustibles (Fig. 3 and 4) · RGPE/RGLE