Air Conditioning or Heat Pump Condensate Clogs or Leaks

Risks: Cooling System Shutdown, Mold Contamination, Costly Water Damage

Condensate Drain Line Leak Risks

Watch out: If the condensate line is not properly installed, if connections are made improperly (as in these photos) or if the drain line or its trap becomes plugged, HVAC system condensate overflow can spill onto and rust and possibly seriously damage the furnace heat exchanger. or cause costly mold contamination or water damage in the buioding.

So during system operation you should periodically confirm that condensate is being discharged properly.

Usually that's a simple visual inspection for water where you don't expect to see it such as under or around the air handler or anywhere along the route of the condensate drain disposal piping.

This sequence of photos shows of an attic air conditioning condensate line what happens when an amateur rigs up a condensate drain in an attic without proper glue, support, and slope.

The plastic piping was not securely supported and when touched, fell apart to spill condensate into the attic floor and into the ceilings below.

Condensate leaks into an attic ceiling risk not only damage to the building but a hidden mold reservoir in the building insulation or on the attic side of the ceiling drywall below.

Since this air conditioning attic system was the same one which showed the dog bowl and kitchen pot in use to catch condensate drips at the air handler unit, the inspector was not remiss in checking the remainder of the condensate drain line rather aggressively.

Condensate leaks from the air handler's internal drip tray (below the evaporator coil) occur if the internal drain is clogged.

When condensate wets the insulation on the interior of the blower compartment there is risk of problematic mold growth in the system.

In warm humid climates such as the Southern U.S., high levels of condensate production in the air handler unit can also result in movement of condensate downstream into the supply duct, forced there by the blower itself.

Missing air conditioning condensate trap: example inspection report language

We did not see a trap on the condensate line itself - usually installed as good practice - ask your HVAC service person about this detail.

It could be required for sanitary or other reasons. CONDENSATE TRAPS have several function including avoiding possible draw of unsanitary air or bacteria back into the building air supply.

Readers who need to clean or unclog a blocked or leaky overflowing A/C or heat pump condensate drain should

see CONDENSATE DRAIN CLEAN & DE-CLOG.

Watch out: When a cooling coil is installed atop a hot air furnace to add air conditioning, if there are A/C condensate leaks that water may drip onto the furnace heat exchanger, risking rust damage, perforation, and future flue gas leaks into the building.

Safety Warning about flue gas leaks: leaks onto a furnace heat exchanger can cause rust damage and holes, risking dangerous carbon monoxide leaks and requiring replacement of the heating system.

Further investigation of the source of leakage and the condition of the furnace heat exchanger is needed promptly - this is a safety concern.

Condensate Pump Leaks & Drain Clog Can Turn off the Air Conditioner

In Florida we have air conditioner drain pumps that pump out the water from condensation.

In tracking down an air conditioner condensate leak, I found that the the condensate pump drain line, a small-diameter PVC pipe, was clogged with water mold.

That was why my air conditioner wasn't kicking on.

It would of ended up costing at least a hundred dollars just for a service tech to fix something as simple as that. I had to take the pump apart and clean it. I took off the PVC drain line coming out of inside air conditioner and blow and clean it all out too. - Jacob Behrends, FL

We suspect that due to the clogged condensate drain line on Mr. Behrends' cooling system, A/C condensate was overflowing into a condensate overflow pan that used a sensor switch that responds to water in the overflow pan by turning off the A/C system.

This design is intended to prevent condensate from overflowing the pan and flooding the building - a possible source of mold or other damage - DF

Photo above: the installer routed the condensate drain to simply spill onto the crawlspace floor - an unacceptable and unsafe installation.

What If No Water is Coming out of the Condensate Drain?

If you don't see condensate coming out of the condensate drain there are several likely explanations:

- the drain system for condensate has become clogged - you need to clear the drain line - check this first

- the system is off or not in cooling mode so not producing condensate

- the air is dry enough in your environment that not much condensate is being produced

- your system uses a condensate pump that has lost power or failed

What If You See Water On the Floor Around Your Air Condioner Indoor Air Handler?

Watch out: if you see water on the floor around the air handler (blower) unit when it is running or has been running, then it's possible that the unit's condensate drain pan leaks, the condensate drain line leaks or is blocked, or if present, the condensate pump is not working.

Details about diagnosing and fixing these problems are at CONDENSATE DRAIN PROBLEMS