Your furnace won't start and it's cold outside. Before calling a technician, work through this systematic checklist — it resolves the most common causes, often without any tools or a service call. In a Minnesota winter, time is critical.
Step 1: Check the Thermostat
Verify: set to HEAT (not COOL or OFF), set temperature above current room temp, fan on AUTO, display is lit (replace batteries if needed), and no accidental schedule changes on a programmable thermostat.
Step 2: Replace the Air Filter
A severely clogged filter causes high-limit shutdown. Pull the filter — if you can't see light through it, replace it immediately and restart the furnace. This is the easiest fix. See our guide on furnace filter types.
Step 3: Check Power
Verify: furnace power switch (wall switch near unit) is ON, circuit breaker hasn't tripped, and the access panel is fully closed — a door safety switch cuts power when the panel is open.
Step 4: Read the Error Code
Look through the sight glass on the furnace door for a flashing LED. Count the flashes — this is the fault code. The code chart is printed on the inside of the access panel. See our full Goodman furnace error code guide for complete details.
Step 5: Check the Gas Supply
Verify: gas shutoff valve on the furnace line is open (handle parallel to pipe = open), other gas appliances work, and propane tank isn't empty. See our guide on gas line requirements in Minnesota.
Step 6: Check the Condensate Drain (High-Efficiency Furnaces)
On 90%+ AFUE furnaces, a clogged condensate drain trips a float switch that shuts down the furnace. Clear the drain line if clogged. See our guide on condensate drain freezing and fixes.
Step 7: Check Exhaust and Intake Venting
In Minnesota winters, PVC venting pipes through the house wall can become blocked by ice or snow. Go outside and verify both pipes are clear — a blocked intake trips the pressure switch. See our guide on pressure switch issues.
Step 8: Manual Reset
Some furnaces have a red reset button near the burner. Press it once — do not press repeatedly. Multiple resets can flood the combustion chamber with gas.
Quick Diagnosis Table
| Symptom | Most Likely Cause | DIY Fix? |
|---|---|---|
| No thermostat display | Dead batteries or no power | Yes |
| Clicks but won't light | Ignitor or gas issue | Check gas first |
| Starts then shuts off quickly | Flame sensor, pressure switch, or limit | No — call tech |
| Error code flashing | Varies — check panel chart | Partial |
| No power to furnace | Tripped breaker or open switch | Yes |
| Condensate backed up | Clogged drain | Yes |
| Intake pipe blocked | Snow/ice accumulation | Yes |
When to Call a Technician Immediately
Call if: you smell gas (leave and call your utility), CO alarm sounds, or furnace locks out repeatedly. For winter emergencies, see our guide on what to do when your Minnesota furnace goes out.
Time for a New Furnace?
If no-start issues are becoming routine on an aging furnace, browse our Goodman furnace collection at Furnace Direct — factory-direct with same-day Minnesota delivery.
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