Goodman Furnace Leaking Water: Causes, Fixes & Costs

Last updated Sep 27, 2026 · By fixme.vip Editorial

Goodman furnace leaking water: what it means

“Leaking water” is not a flash-code on Goodman furnaces — it is a physical symptom, so your control board may show no fault at all, or it may show a pressure switch code (2 or 3 flashes) as a downstream effect of water backing up.

Flash-code meanings differ between Goodman/Amana control board generations, and some newer boards use a 7-segment display or a different sequence — always confirm what your flashes mean against the diagnostic label printed on the inside of the blower-door panel for your specific board.

Water at a Goodman furnace almost always comes from one of three systems:

1. The condensate drain system on high-efficiency (90%+ AFUE) condensing furnaces, which by design produce several gallons of acidic water per day of runtime.
2. The evaporator (AC) coil and drain pan sitting on top of the furnace, which leaks in cooling season and drips down onto the furnace cabinet.
3. A cracked secondary heat exchanger on a condensing furnace, which lets condensate escape where it shouldn’t.

If you have an 80% AFUE (non-condensing) Goodman furnace, it has no condensate drain — so water there is almost certainly from the AC coil above it, not the furnace itself.

This is rated pro because distinguishing a simple clogged drain from a cracked heat exchanger, and safely drying out electrical components, is technician work.

Goodman furnace leaking water: common causes, ranked by probability

1. Clogged condensate drain line or trap. Algae, dust, and mineral sludge block the drain, so condensate backs up and overflows from the collector box or trap. This is by far the most common cause on condensing Goodman furnaces.
2. Clogged or overflowing AC condensate drain (cooling season). The evaporator coil above the furnace overflows and drips onto the cabinet. Common when the furnace only “leaks” while the AC runs.
3. Cracked or loose condensate trap / disconnected drain hose. Goodman traps and rubber hoses can crack, split, or work loose, dumping water at the base of the furnace.
4. Blocked or sagging flue/vent condensate. Improper PVC pitch lets condensate pool and drain back into the furnace instead of out.
5. Clogged or dirty inducer / collector box drain port. Water can’t clear the collector box and overflows, sometimes tripping the pressure switch.
6. Condensate pump failure (where installed in basements below the drain). A failed pump lets its reservoir overflow.
7. Cracked secondary heat exchanger. Least common but most serious — condensate escapes internally and leaks from the cabinet. Requires professional inspection and often replacement. Because this is a gas appliance, a cracked heat exchanger can also allow combustion gases, including carbon monoxide, to escape: shut the furnace off and do not run it again until a technician has inspected it, and make sure you have working CO alarms on every level of the home. If a CO alarm sounds, or anyone has headaches, nausea, dizziness, or flu-like symptoms that improve when they leave the house, get everyone outside and call 911 or your gas utility from outside.

How to fix Goodman furnace leaking water: safe checks first

Turn the furnace off at its dedicated wall switch before touching anything wet.

• Confirm the source. Does water appear only when the AC runs (points to the coil) or during heating (points to the furnace condensate system)?
• Check and replace the air filter. A clogged filter can ice an AC coil, which then floods the pan when it melts.
• Look at the condensate drain line. If you can see a PVC drain or a clear/rubber hose outside the furnace cabinet, check for an obvious clog or a line that has popped off its fitting. You may reseat a hose only if it is visible and reachable outside the cabinet — on many Goodman condensing models the hoses and trap sit behind the cabinet door, and those are off-limits.
• Check the condensate pump (if you have one). Make sure it’s plugged in and the reservoir isn’t overflowing. Many have a reset — cycle its power once.
• Clear a floor drain the line empties into, if it’s backed up.
• Verify the thermostat is set correctly and the breaker hasn’t tripped.
• Soak up standing water with a wet/dry vac to protect the control board.

Do not open the furnace cabinet, remove the trap, or probe the collector box — that’s technician work.

How a technician will diagnose it

• Runs the furnace and traces the water path to identify whether it’s condensate, AC coil, or heat exchanger origin.
• Removes and inspects the condensate trap and hoses for cracks, sludge, and blockage; flushes the drain line.
• Inspects the collector box and inducer drain port for clogs and corrosion.
• Checks flue/vent pitch and terminations for pooling or backflow.
• Tests the pressure switch and tubing if water backup tripped a pressure fault.
• Inspects the secondary heat exchanger with a camera or pressure/combustion analysis if simpler causes are ruled out.
• Checks the AC drain pan and evaporator coil if leaking correlates with cooling operation.

A good tech shows you the actual leak source before quoting a repair — insist on that before approving heat-exchanger-level work.

Symptom, cause and what to do

Goodman furnace leaking water repair cost

Prices vary by region and access. If a cracked heat exchanger is confirmed on an older furnace, weigh repair against a full replacement.

Related codes

Flash-code meanings vary by control board generation — check the diagnostic label inside the blower door before matching your furnace to any of these.

• Goodman Furnace 2 Flashes: Pressure Switch Stuck Closed — condensate backup can trip this.
• Goodman Furnace 3 Flashes: Pressure Switch Stuck Open — blocked drains and inducer ports relate here.
• Goodman AC Running But Not Cooling: Causes & Costs — for cooling-season coil and drain issues.
• Goodman Furnace Keeps Shutting Off: Causes & Fixes — if water backup causes intermittent lockouts.