Run capacitor
Common no-start and weak-compressor failure point. Match the microfarad and voltage rating.
Amana / Goodman Furnace 3 Flash Error Code — What It Means
Both Amana and Goodman furnaces (Amana is a Goodman brand and uses the same control board platform) flash 3 blinks on the LED status indicator when the draft pressure switch circuit has faulted. The 3-flash code means the inducer pressure switch did not confirm adequate draft pressure before or during the heat cycle. Amana and Goodman users searching for either brand’s 3-flash code will find the same root cause and the same repair process — the control boards, pressure switches, and diagnostic logic are identical across both brands.
Common Causes
- Blocked or kinked pressure switch hose — The rubber hose connecting the inducer housing port to the pressure switch is the most common physical cause; it collapses, clogs with condensate, or cracks over time.
- Failed pressure switch — The switch diaphragm fails and won’t close even with adequate draft. Switches fail more quickly on high-efficiency models where the hose carries warm condensate-laden air.
- Failed inducer motor or capacitor — An underperforming inducer motor can’t generate enough negative pressure to close the pressure switch.
- Blocked intake or flue vent — A blocked PVC intake or exhaust pipe prevents proper airflow through the heat exchanger, starving the inducer of the pressure differential needed to close the switch.
Step-by-Step Fix
- Inspect and clear the pressure switch hose — Power off the furnace. Locate the rubber hose(s) running from the inducer to the pressure switch. Look for kinks, cracks, or condensate pooling. Blow through it to verify it’s clear.
- Test the pressure switch — Disconnect the hose from the switch port and apply suction (mouth or hand pump). A good switch clicks closed at approximately -0.5” to -1.0” WC. No click means the switch has failed.
- Verify inducer operation — Restore power and watch/listen to the inducer during a heat call. Full-speed startup within a few seconds is normal. Slow or no rotation points to a seized motor or failed capacitor.
- Check the venting system — Go outside and inspect the PVC intake and exhaust terminations for blockage — bird nests, insect screens clogged with debris, or ice are common in winter.
- Reset and test — After repairs, cycle the thermostat to call for heat. If 3 flashes clear and the furnace lights, run through two full heat cycles before calling the repair complete.
Parts Often Needed
| Part | Notes |
|---|---|
| Pressure switch | Goodman/Amana switches are model-specific; verify part number by model tag |
| Inducer capacitor | Test before replacing the motor; often cheaper cause of slow inducer |
| Pressure switch hose | Available by the foot at HVAC supply houses |
| Inducer motor assembly | Replace when motor shaft is seized or winding tests open |
Technician Tips
Goodman furnaces use a simple LED flash system on the control board. The diagnostic LED is usually visible through the blower compartment window. Count the flashes between pauses — that’s your error code. One flash = normal operation. Two flashes = pressure switch fault. Three flashes = limit switch. Four flashes = flame sensor. Goodman flame sensors are notorious for carbon buildup — cleaning with emery cloth every 2-3 years prevents most lockout calls. The control board on GMS8 and GMSS9 models is particularly sensitive to voltage fluctuations — if you see multiple different codes, check the transformer output (should be 24VAC ±10%).
Prevention: Install a whole-house surge protector on the furnace circuit to prevent board damage from power spikes.
Need Replacement Parts?
Before ordering, match the furnace part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
When to Call a Pro
If all mechanical components check out and 3 flashes persist, the heat exchanger may have a crack that disrupts the pressure dynamics in the flue system. Heat exchanger inspection requires a licensed HVAC technician — do not continue operating the furnace if a cracked heat exchanger is suspected.