Payne PG96VTA Error Code 43: Low-Heat Pressure Switch Open While High-Heat Pressure Switch Is Closed
What Does Code 43 Mean?
Status code 43 on the Payne PG96VTA indicates that the low-heat pressure switch is open while the high-heat pressure switch is closed. This is an abnormal condition because if the high-heat switch can close (indicating sufficient draft at high speed), the low-heat switch should also be able to close since it requires less suction.
This inconsistency most commonly points to a plugged condensate drain. When condensate water cannot drain properly, it backs up and can interfere with the low-heat pressure switch operation while the higher suction from high-heat mode is still sufficient to close its switch.
Other possible causes include a stuck open low-heat pressure switch, disconnected or obstructed pressure tubing, improper pressure switch wiring, or low inlet gas pressure if a low gas pressure switch (LGPS) is installed.
Common Causes
When to Call a Professional
Contact a licensed HVAC technician if:
- The condensate drain is clear but code 43 persists
- You see water pooling around the furnace or in the vent piping
- You suspect a faulty low-heat pressure switch
- The pressure tubing appears disconnected or damaged
- The code returns after every heating cycle
✓ Verified against manufacturer service manual — March 2026