57 Pressure switch stuck open

What the control is telling you

802P and RGPE/RGLE: the high-fire pressure switch (HPC) did not close (or opened) when the inducer ran high speed for high fire. R95P (single pressure switch): pressure switch did not close; after 60 seconds of inducer run the control goes into a 5-minute soft lockout and retries. Not stored back-to-back in the RGPE fault buffer.

Applies to: 802P/80MDP (802PA050-150); R95P (R95PA040-115); RGPE/RGLE 2-stage 80+

Likely causes

• Weak inducer or not reaching high speed
• Hose cracked, disconnected, kinked or water-filled
• Blocked vent/intake, excess vent length or elbows
• Blocked heat exchanger or condensate backing up (R95P)
• Wind / downdraft
• Faulty switch or wiring

Test and repair steps

1. Check pressure switch hoses for cracks, kinks, water or moisture.
2. Check vent and intake for blockage; verify vent length and elbows are within manual limits.
3. Confirm the inducer is wired correctly and runs at normal speed.
4. 802P check 24VAC is on W2 for high heat.
5. R95P check heat exchanger and condensate trap/drain for blockage.
6. Check switch and its wiring; replace if it will not close with proper draft.

Settings for these units

• Clearance to combustibles (all models) · R95P
• 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