Goodman 3 flashes — Pressure switch stuck open

What this error means

The draft pressure switch won't close: the furnace can't prove its venting is safe. Blocked exhaust or intake pipes (winter classics: snow, ice, nests), a failing inducer motor, kinked switch tubing, or a condensate clog on high-efficiency models.

Symptoms

• No ignition; inducer may run continuously
• 3-flash pattern
• Cold-snap timing

Try this first (safe DIY steps)

1. Check and clear the exterior intake/exhaust terminations
2. High-efficiency models: check the condensate drain isn't clogged/frozen
3. Power off 30 seconds, on; one retry

Safety: power off before any physical intervention. Never bypass covers or interlocks — fuser areas run hot enough to burn.

When to call a technician

Recurring with clear venting — pressure switch ($150–400) or inducer ($400–1,100) diagnosis.