Goodman Furnace: High stage pressure switch open, furnace on low stage only
High stage pressure switch open, furnace on low stage only on a Goodman furnace: Induced draft blower runs but the furnace only operates on low stage.
Applies to: 34.5 in chassis gas furnaces
Common causes of high stage pressure switch open, furnace on low stage only
- Pressure switch hose blocked, pinched or connected improperly
- Blocked flue and/or inlet air pipe, blocked drain system, or weak induced draft blower
- Incorrect pressure switch set point or failing switch contacts
- Loose or improperly connected wiring
How to fix high stage pressure switch open, furnace on low stage only: step by step
- Turn power off before repair.
- Replace the pressure switch with the correct part.
- Inspect the pressure switch hose and repair or replace if needed.
- Inspect flue and/or inlet air piping for blockage, length, elbows and termination. Check the drain system.
- Check induced draft blower performance and correct as needed.
- Correct the pressure switch set point or contact action.
- Tighten or correct the wiring connection.
- Replace the induced draft blower with the correct part if it is weak.
Safety: Gas, electrical and refrigerant work must be done by a licensed technician. Turn off power and gas before servicing, never bypass a safety control, and always follow the manufacturer's manual for your exact model.
If the unit shows an error code, look it up: Goodman Furnace codes
Source: Goodman GMVC96 Service and Troubleshooting, p. 61. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.