What causes Goodman Gas Furnace 3 flashes?

Pressure switch hose disconnected, cracked, pinched, blocked, or connected to the wrong port. Water in the pressure switch hose or switch (often from a mis-routed hose). Blocked or restricted flue/vent or combustion air intake pipe (debris, nests, snow/ice at the termination). Improper vent length, too many elbows, or a vent with low spots that trap water (90%+ condensing models). Clogged or frozen condensate drain/trap backing water into the inducer or collector box (condensing models). Weak or failing induced draft blower (inducer motor), or an object stuck in it. Faulty pressure switch (incorrect setpoint or contacts not closing) or loose/incorrect wiring. Less commonly, a faulty integrated control board — replace only after all other checks.

How do I fix Goodman Gas Furnace 3 flashes?

Count carefully: look through the sight window on the blower door. 3 short flashes + pause is this code; 2 flashes is a different fault (switch stuck CLOSED). Note the code before cutting power — some boards clear it on reset. Check outside: inspect the intake and exhaust pipe terminations for snow, ice, leaves, nests, or insect screens that are clogged. Clear only what you can reach safely. Power OFF at the furnace switch/breaker before opening panels. Inspect the small rubber pressure switch hose from the switch to the inducer (or collector box) port: it should be firmly attached, not cracked, kinked, or holding water. Blow it out gently (away from the switch) if it has water, and verify it slopes so water drains away. Condensing (90%+) furnaces: check the condensate drain hoses and trap for clogs or freezing; clean the trap and make sure hoses slope downward. Listen when restarting: an inducer that hums but doesn't spin, or sounds like it's sloshing water, points to a bad inducer/capacitor or water in the inducer — that's a pro job. Reset: turn the thermostat off for more than 5 s and less than 20 s, or cut power for at least 5 s. If the code returns, stop and call a pro.

When should I call a pro for Goodman Gas Furnace 3 flashes?

The code keeps returning after you've cleared the vent terminations and checked the hose. You'd need to test 24 VAC across the switch terminals or measure inducer pressure with a manometer (the Goodman checkout procedure). The inducer motor hums, won't start, or has water inside it. Vent pipe needs re-sloping, re-routing, or has too many elbows/too long a run. You smell gas or suspect a cracked heat exchanger or venting leak — leave the house and call the gas utility. Never bypass or jumper the pressure switch; it prevents carbon monoxide hazards.

Code: 3 flashes🔥 Goodman Gas Furnace

Goodman Furnace 3 Flashes: Pressure Switch Stuck Open (Meaning, Causes, Fixes)

Q: What does Goodman Gas Furnace 3 flashes mean?

Three short flashes then a pause on a Goodman furnace control board LED means the inducer (draft) blower is running but the pressure switch has not closed. The furnace will not light until the switch proves there is proper draft. Per Goodman's service literature, after the induced draft blower is energized the control waits for the pressure switch to close. If it doesn't, the LED flashes 3 times followed by a pause. On many Goodman integrated controls, if the switch does not close within 5 minutes the control enters a 1-hour lockout and then automatically retries. Symptom: the inducer runs continuously with no further furnace operation (no ignitor glow, no burners).

Reviewed 2026-10-21 · Based on 5 manufacturer & service sources

What the code means

Per Goodman's service literature, after the induced draft blower is energized the control waits for the pressure switch to close. If it doesn't, the LED flashes 3 times followed by a pause. On many Goodman integrated controls, if the switch does not close within 5 minutes the control enters a 1-hour lockout and then automatically retries. Symptom: the inducer runs continuously with no further furnace operation (no ignitor glow, no burners).

Likely causes

Pressure switch hose disconnected, cracked, pinched, blocked, or connected to the wrong port
Water in the pressure switch hose or switch (often from a mis-routed hose)
Blocked or restricted flue/vent or combustion air intake pipe (debris, nests, snow/ice at the termination)
Improper vent length, too many elbows, or a vent with low spots that trap water (90%+ condensing models)
Clogged or frozen condensate drain/trap backing water into the inducer or collector box (condensing models)
Weak or failing induced draft blower (inducer motor), or an object stuck in it
Faulty pressure switch (incorrect setpoint or contacts not closing) or loose/incorrect wiring
Less commonly, a faulty integrated control board — replace only after all other checks

Safe DIY checks

⚠ Before you start

Turn off power at the furnace/HVAC service switch and the breaker before opening panels. Shut the gas valve before any work near the burners, and never disconnect or alter the gas line. If you smell gas, leave the house and call your gas utility.

Count carefully: look through the sight window on the blower door. 3 short flashes + pause is this code; 2 flashes is a different fault (switch stuck CLOSED). Note the code before cutting power — some boards clear it on reset.
Check outside: inspect the intake and exhaust pipe terminations for snow, ice, leaves, nests, or insect screens that are clogged. Clear only what you can reach safely.
Power OFF at the furnace switch/breaker before opening panels.
Inspect the small rubber pressure switch hose from the switch to the inducer (or collector box) port: it should be firmly attached, not cracked, kinked, or holding water. Blow it out gently (away from the switch) if it has water, and verify it slopes so water drains away.
Condensing (90%+) furnaces: check the condensate drain hoses and trap for clogs or freezing; clean the trap and make sure hoses slope downward.
Listen when restarting: an inducer that hums but doesn't spin, or sounds like it's sloshing water, points to a bad inducer/capacitor or water in the inducer — that's a pro job.
Reset: turn the thermostat off for more than 5 s and less than 20 s, or cut power for at least 5 s. If the code returns, stop and call a pro.

🛠 When to call a pro

The code keeps returning after you've cleared the vent terminations and checked the hose.
You'd need to test 24 VAC across the switch terminals or measure inducer pressure with a manometer (the Goodman checkout procedure).
The inducer motor hums, won't start, or has water inside it.
Vent pipe needs re-sloping, re-routing, or has too many elbows/too long a run.
You smell gas or suspect a cracked heat exchanger or venting leak — leave the house and call the gas utility. Never bypass or jumper the pressure switch; it prevents carbon monoxide hazards.

Parts that commonly fix it

Always match the part number to your exact model.

⚙

Pressure switch (exact OEM part number for your model)

Match the part number printed on your existing switch (inches W.C. rating matters). Use only the proper replacement part.

[affiliate link slot: AFFILIATE_SLOT_PRESSURE_SWITCH]

⚙

Pressure switch hose / tubing

Cheap fix for cracked or brittle hoses.

[affiliate link slot: AFFILIATE_SLOT_HOSE]

⚙

Induced draft blower (inducer motor) assembly

Model-specific; usually a pro install.

[affiliate link slot: AFFILIATE_SLOT_INDUCER]

⚙

Condensate trap / drain kit (90%+ models)

For clogged or cracked traps.

[affiliate link slot: AFFILIATE_SLOT_TRAP]

⚙

Integrated control board

Last resort after all other checks.

[affiliate link slot: AFFILIATE_SLOT_BOARD]

Sources

Last reviewed 2026-10-21. Always confirm against the manual for your exact model number.