55 Pressure switch stuck closed

What the control is telling you

802P and RGPE/RGLE: the high-fire pressure switch (HPC) is closed when it should be open. R95P (single pressure switch): pressure switch stuck closed when it should be open. Furnace will not start a heat cycle.

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

Likely causes

• Switch contacts welded/stuck
• Shorted or miswired wiring
• Water in switch or hose

Test and repair steps

1. With the inducer off, check the pressure switch - must be open.
2. Check wiring for shorts.
3. Check switch and hose for water or moisture.
4. Replace the switch if stuck closed; check the IFC only if wiring and switch are good.

Settings for these units

Clearance to combustibles (all models) · R95P

Same values for R95PA040 through 115.

Column order read from a rotated drawing header - confirm on the furnace clearance label.

Filter sizes as shipped, upflow (Table 19) · RGPE/RGLE

Use one filter location only - do not double-filter or filter the supply side.

21 in./100K: cut 3-1/2 in. off filter and frame for a side filter; 24-1/2 in./125K: cut 7 in.

• 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

Models that show this code

21 models in Rheem/Ruud 802P / 80MDP 80% two-stage furnace (UT 1028-928 IFC), R95P, RGPE/RGLE

Other codes on the same units

• 33 Rollout switch (MRLC) open
• 44 Low pressure switch closed (stuck)
• 45 Low pressure switch open - inducer high speed
• 46 Low pressure switch open - inducer low speed
• 57 Pressure switch stuck open
• 58 Water sense circuit open
• 59 Water sensed / blocked drain
• 60 Blower fault - running (BLWR FLT-RUN)