31 High-heat pressure switch or relay did not close or reopened

What the control is telling you

The high-heat pressure switch (HPS) or its relay did not close, or opened again, during high-heat operation.

Applies to: 59TP6A two-stage variable-speed ECM multipoise condensing gas furnace, all sizes (040-10 to 120-22)

Likely causes

• Defective control relay (HPSR)
• Gas valve miswired
• Any of the code 32 causes (venting, tubing, drain, inducer)

Test and repair steps

1. Warning: Shut off 115-V power and gas, and lock/tag out before working inside the furnace; there may be more than one power source.
2. Check gas valve wiring against the wiring diagram (Fig. 67).
3. Go through all code 32 checks vent, tubing, condensate drain, inducer.
4. If HPS fails to close while LPS is closed, the furnace runs low-heat gas flow for up to 2 minutes after ignition waiting for HPS.
5. If the switch and venting are good, suspect the relay on the control and replace the control.

Settings for these units

Filter sizes by casing width and filter cabinet · 59TP6A

No internal filter rack in this furnace - an external filter is required.

Side-return filters can differ in size - measure the existing filter.

Minimum clearances to combustibles · 59TP6A

Keep 1 in. from combustibles to supply duct for 36 in. horizontally from the furnace.

Do not set on carpet or combustible tile; downflow on combustible floor needs the accessory floor base unless on a matching coil casing.

Models that show this code

8 models in 59TP6A

Other codes on the same units

• 23 Pressure switch did not open
• 24 Secondary (24 V) fuse open
• 25 Invalid model selection or setup error
• 32 Low-heat pressure switch did not close or reopened
• 33 Limit circuit fault
• 34 Ignition proving failure
• 43 Low-heat pressure switch open while high-heat switch closed
• 45 Control circuitry lockout