HVACopediaGoodman · Furnace troubleshooting
Check blower (inducer) pressure switch
What is going on
The pressure control stops combustion if venting is restricted or blocked. A/GMVC96 and A/GCVC models also have a front cover pressure switch in series with the gas valve. It blocks the valve if condensate backs up in the secondary heat exchanger.
Likely causes
- Restricted or blocked vent pipe
- Improperly connected or plugged condensate drain
- Defective pressure switch
Check in this order
- Shut off power and remove the burner compartment door.
- Remove the wires from the pressure switch terminals.
- Disconnect the pressure hose and connect an inclined manometer through a 1/4 in. tee to the inducer tap.
- With an ohmmeter across the switch terminals and the inducer running, the switch should close.
- If it does not close, compare the negative pressure to the switch closing point.
- If the pressure is fine, replace the switch. If pressure is low, check the inducer and venting.
Applies to: Blower pressure switch and front cover pressure switch
More furnace guides
- Airflow lower than demanded, furnace runs on low stage when high stage is expected
- Alternate combustion air opening (upflow or horizontal)
- Alternate vent/flue location (upflow or horizontal left)
- Annual inspection checklist
- Auxiliary limit control (location and purpose)
- Auxiliary limit switch open (blower compartment)
Take it to the job
All guides, error codes and tips work offline in the HVACopedia app.
Source: Goodman GMVC96 service manual, p. 53. Written in our own words; check the manual for your exact model.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.