HVACopediaGoodman · Furnace troubleshooting
No ignition - voltage checks at the ignition control
What is going on
Step-by-step live checks to find where the sequence stops. Take care, line voltage is present.
Likely causes
- No 120 V to the control or door switch open
- No 24 V from the transformer or thermostat
- Blown fuse
- Inducer or igniter circuit not powered
Check in this order
- Measure 120 V at the control between Line 1 (hot) and Line 2 (neutral). None: check the door switch and harness continuity.
- Measure 24 V from W to C. None: check the transformer, thermostat and wiring. If the transformer has 24 V but the board shows about 13 V between C and R, check for a blown fuse.
- Measure 120 V to the inducer between pin 1 of the 2-pin plug and neutral. None: replace the control.
- With the inducer running, measure 120 V to the igniter between pin 2 of the 2-pin plug and neutral during warm-up. None: check the pressure switch.
- After warm-up, check for 24 V at the gas valve. It shows for about 7 seconds only if flame is proven.
Applies to: GMES9, GCES9, AMES9, ACES9, VMES9, VCES9 (single stage, 92% and 96%)
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
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Source: Goodman Service and Troubleshooting GMES9*/GCES9*/AMES9*/ACES9*/VMES9*/VCES9* (RS6612016r3) , S-313 Checking Integrated Ignition Control Boards p.45. 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.