I bought my house about 17 years ago, and the heat pump was already installed. I've handled general maintenance myself, and brought in a pro on occasion to replace major parts. I'm pretty sure that everything has been replaced at this point except for casing... no joke!

Forgive me for not knowing proper terms for things, I'll describe as best as I can.

Yesterday, I discovered that there was water all in my basement, under the air handler. Upon investigation, I could see that the small condensate tank was full, and the discharge hose wasn't sucking the water out so it overflowed.

That's happened before, I usually just disconnect the discharge valve, clean it with a Q-tip, and it's good to go. But this time it looked like the pump wasn't coming on! The power has flickered a few times lately, so I was worried that something had fried. I unplugged it and checked the breakers, but it was all good. I let it sit for about 15 minutes to reset, but when I plugged it in it still didn't come on.

I went ahead and cleaned the discharge, but it still didn't work. I used a small spike to release the check valve so it would flush the hose in to a bucket, then cleaned it again and put it back... still no go.

Then I used a wet/dry vac to suck the water out of the tank, and THEN it worked! Maybe the pump wasn't coming on because it was too full? That feels backwards, but it's my only explanation.

Thinking there could be some mold or algae in the tank, I turned the pump off again and then poured in about 1/2 cup of Clorox and filled the tank with hot water. I let it sit for about 10 minutes then turned on the condensate pump, and it sucked it all out.

Everything seemed like it was good... but then tonight, water was everywhere again!

This time I didn't unplug the pump or disconnect the discharge hose, I just sucked a little water out of the tank with the wet/dry vac. I had no more than sucked out water for a second before the pump kicked on and sucked out the rest of the water itself!

I did another round of Clorox and hot water, and I kept an eye on it for an hour and everything seemed fine again. But fool me once ...!

What do you all think? Does this sound like an issue of something failing, or just a clog that I may or may not have gotten?

If it helps, here are the model numbers for everything:

Condensate pump: Hartell KT-15-1UL

Air handler: Carrier FX4ANF036

And here's a pic of the discharge hose that I'm talking about:

I had cleaned the coils about 2 months ago, using condenser coil spray and a grill brush. It's possible that some of the gunk from the coils ended up in the drain tank, but that's a long time to just NOW be a problem...