You know, there are cameras on every smart phone... The tech could make a much stronger case by showing you the frozen coil and/or the condensation.

Under certain conditions the coil can ice up and if it did, all bets are off on containing the resulting water in the pan. Make sure that all of the things that contribute to coil icing have been addressed including faulty TXV.

Also consider if there's anything else you can do to protect the ceiling. Since you have a cutoff, a larger plastic sheeting or such might be a reasonable approach.

The smart phone idea is a good one. In this case, though the unit had shut off hours before, so any ice was long gone. I was looking over the tech's shoulder the whole time, so I saw pretty much what he saw, just without the knowledge he has.

I have been wondering about additional water containment. But it's not a realistic option, because the volume of water means no containment will be good for more than a day (if that). It is very humid in Tennessee in the summer.

Ultimately the only thing that will work is an air conditioner that never leaks ever. We can't live with the daily fear of water coming through our ceiling.

Also keep in mind: a simple thing that could cause this is the air handler being out of level.. If that was the case, the water would build up in the internal pan and overflow (finding it's way out of the jacket into the overflow pan).Go up there with a level and be sure that it's correct. If not, get some cork pads/shims and level it as needed. The unit being undercharged or a very dirty air filter or evaporator coil can cause it to ice up as well..

...Also, I would question why the previous tech used a metal pan again, the plastic style are much longer lasting ...

Don't like your AC techs, neither one of them good. call some one else. First. ice built up was caused by low on charge, not TVX, he just want your $1000. (spend a few minutes up there simply can not tell if TXV is good or bad.) Second, when a drain pan was put in, he should put a drain pipe in there, so water can be drained outside, we called this secondary drain. with this secondary drain pipe, even your AC leaks, it should not damage your ceiling. Now you should get the secondary drain pipe installed and system properly charged, and then see what will happen, go one step a time.

"Under certain conditions the coil can ice up and if it did, all bets are off on containing the resulting water in the pan."

The pan should cover any area that could leak from the coil/air handler. The only way I can think of is if the pan capacity is less than the volume of ice on the coil and it doesn't have a secondary drain (I have vertical and horizontal air handlers that have frozen over and never been a problem).

Have the guy run a secondary drain from the pan into the primary drain if there isn't one there right now to address the leaking problem. You need to address the coil freezing problem, if that is occurring. Check you filter and refrigerant charge before you replace the TXV (he should have done this - ask him what he found).

Hey, thanks for all the responses.
OK, so check the air handler is level, I can do that.
The tech who came yesterday did check the charge and said there was good pressure (but he also recharged it). He ran his freon detector all over and didn't find a leak.

I agree about putting in an auxiliary drain. It was crazy of the first guy not to do that. HOWEVER - since the cut-off in the pan is working, the pan should not overflow. Either the pan is leaking or the water is condensing on something that is outside the area of the pan.

Or, as sktn77a says, the volume of ice is too big to be contained by the pan when it melts. If that's the case, the cut-off would turn off the unit, but the ice would keep melting.
Possible. That would be a heck of a lot of ice.

I am afraid to turn on the unit to see if it ices up.

I could call another tech = another call-out charge :(
But the company I'm using is the biggest and most reputable in my town.

I guess i don't understand the point of the secondary drain.
I've seen when drains clog with mold, but that's only after many years.... so I don't know what the secondary drain would accomplish here.

A malfunctioning TXV could cause it to ice, as well as low charge and restricted airflow... but usually you see that in a cap tube system since the TXV is regulating the flow into the evaporator based on evaporator temp.

I understand that it produces a lot of water, but you have a cutoff system in place. A secondary water barrier should prevent water damage as long as the cutoff is working.

It's not so much that the volume of ice is too big to be contained by the pan... it's that it extends beyond the pan to the suction line and the possibly the coil housing.

If it were iced up like that, you should be getting almost no airflow through the unit.

"The tech who came yesterday did check the charge and said there was good pressure (but he also recharged it)." ... those things are mutually exclusive.
You don't add refrigerant to a unit that is properly charged. What's more, you don't guess at the charge and you can't properly charge a unit where the TXV has failed because sub-cooling is the the only acceptable way to determine the proper charge.

Look, if it's icing, you really need to see that. You can't guess unless you see why the unit is leaking... you have already done that and you've had to repaint the ceiling a couple of times.

Did you ever find a solution for you leaking condensate pan? I recommend you use Pancrete - Self-Leveling, so you just pour right into the pan, and it is a permanent fix, so you never have to look at corrosion again.

You can view Pancrete through the product page on the link listed below. If you have any questions, e-mail me at Chasity@cleanac.com

Here is a link that might be useful: Pancrete

Pancrete - Self Leveling - Air Handler Refurbishment