Run capacitor
Common no-start and weak-compressor failure point. Match the microfarad and voltage rating.
Amana Furnace 3 Flash Error Code — What It Means
Three flashes on an Amana furnace LED indicates a draft pressure fault — the pressure switch did not close during the induced draft motor startup sequence. Amana is a Daikin brand and shares controls with Goodman, so the diagnostic logic is identical across those platforms. The 3-flash code appears before any ignition attempt because the board requires proof of draft before allowing the gas valve to open. The pressure switch physically measures the difference in air pressure between the inlet and the vent outlet; if the draft motor isn’t moving enough air, the switch stays open.
Common Causes
- Clogged condensate drain — On 96% AFUE Amana units (AMVM97, AVPTC, etc.), condensate builds up in the collector box. When the drain backs up, water can block the pressure switch port or flood the hose connection, preventing switch closure.
- Blocked PVC vent — Ice formation at the exhaust pipe termination during cold weather is a very common cause on high-efficiency units. Insects and debris also block intake pipes.
- Cracked pressure switch hose — The rubber hose from the inducer housing to the pressure switch develops cracks at its connection points. Any leak breaks the vacuum signal.
- Failed inducer motor or capacitor — The motor must reach full RPM before the pressure switch closes. A weak or dead start capacitor is a common failure that leaves the motor unable to build sufficient draft.
Step-by-Step Fix
- Check the vent pipes outside — Walk to the exterior vent termination. Clear any blockage in both the exhaust (usually white pipe) and intake (second pipe on 2-pipe installations). In winter, check for ice.
- Inspect the pressure switch hose — Trace the small rubber hose from the draft motor to the pressure switch. Feel for cracks, especially at the hose ends. Disconnect and blow through — should pass air freely.
- Clear the condensate system — On 90%+ units, remove the condensate trap from beneath the secondary heat exchanger and rinse it out. Pour water into the collector box and confirm drainage.
- Check draft motor startup — At the call for heat, the motor should spin within 5 seconds. Listen. If you hear a hum without rotation, test and replace the run capacitor.
- Reset the system — Power cycle after addressing the root cause. If the pressure switch closes (audible click), ignition proceeds and the fault clears.
Parts Often Needed
| Part | Notes |
|---|---|
| Inducer motor run capacitor | Most common fix when motor hums but won’t start |
| Pressure switch | Amana/Goodman often use B1370738 or similar; check WC rating |
| Pressure switch hose | 3/8” ID; sold by the foot |
| Condensate trap (Amana part) | Replace if cracked or permanently fouled |
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 but the 3-flash code persists, a tech should use a manometer to verify actual system pressure against the switch rating. Wrong-rated pressure switches will produce this fault indefinitely.