Why is Water Dripping from Unit?
28 Jan 2026 · 2 min
Derek Cole explains how HVAC split systems work and why water drips from your unit. A clogged primary drain line forces condensate into the secondary line, which can overflow and damage your ceiling. Call a technician if you see water dripping.
Chapters
That's a good question.
The reason that is happening is because.
On some installations of an upstairs, you have two parts. So you have a split system. You have that downstairs part outside, that's the condenser. Upstairs you're gonna have the air handler, which houses the coil and the fan to blow the air through the duct system. So some applications have multiple drain lines. So when you're talking about air conditioning.
You'Re talking about removing heat from the.
Part of that removal of the heat, especially in this area, is dehumidification. We talked about that last week. The air conditioner is a dehumidifier. So to do that, moisture is taken.
Out of the air.
So the result of that, obviously, is water. So that water has to go somewhere.
So upstairs you have a drain line. It sounds like you have a drain line, a primary drain line, and a secondary drain line. The primary drain line should be functioning somewhere where you cannot see it.
It'll be outside, obviously dripping somewhere.
The secondary drain line, when that's installed.
They always put it in a place.
Where you can see the water dripping.
I've even seen it.
I've even seen it in the front.
Of a house at the front door. You know, it'll drip basically on your.
Head when it starts dripping, like, oh.
My goodness, that'll get your attention.
But when that secondary line is dripping, it means the primary is clogged. So you're fixing to have a serious problem on your hands. So I would get my contractor or.
Us out there to see why that.
Drain line is clogged in. The primary drain line is clogged, and then check the secondary.
But it is working properly, and you're cool.
So you might not think there's a.
Need to call somebody, but I would.
Go and do that.
Otherwise you risk the problem of having.
That secondary drain line get clogged. And then you'll have an overflow on your ceiling. You have ceiling damage, and you're going to have all kind of problems there.
So that is not a good sign.
When you can see the water dripping out of the secondary drain line, which will be somewhere usually where you can see it in front of a window.
Or in front of your front door. In that case, that is an indication.
That we have a problem. So you see the problem.
So you call somebody about the problem.
Sam.
More from Derek


713. Fan "On" or "Auto"? The Thermostat Setting That Could Be Making Your Home More Humid


712. Why Is My Upstairs Always Hotter Than Downstairs? The Truth Every Homeowner Should Know