Dottie wrote:
I have a Trane air conditioner that was installed in 2007. I did not
buy the extended warranty. I have had it checked every spring ...
and until last year there was no problem.

In April a technician came out and checked it -- spent a long time
with it and also tried very hard to sell me on letting the company
clean my dryer vents. I declined.

In June the a/c started running long periods and dripping water...
the drain pipes were not clogged... the man who came out and
diagnosed the problem said a valve was bad and that the refrigerant
was over filled. He had to order the valve - and it took several
days. He said the part rarely failed. Someone on this board told me
later that "over-filling" could cause it to fail. Anyway, it has
been working o.k. since then - until last week. (It costs me $1069
to fix). Last week it was hot and humid (Florida) and I turned it
on... it started dripping water again, same as before. I turned it
off -- the next day it was cold again and I used it to heat the
house.

Yesterday I called the company and asked them to send someone out to
check it (after making sure the part they put in was still under
warranty). I asked the name of the techie coming out and when I
found out it was the one who started this string of events I asked
her not to send him. Went to the grocery store and he was working on
an a/c one street over -- I recognized him. Anyway, my question is
-- how long should a Trane last and when does it become unwise to fix
it -- appreciate help with this. Thanks.

Inasmuch as you're in Florida, did the technician try to sell you some swamp
land?

An air conditioner cannot drip water. Water is not involved in the a/c
piping system. Period.

What CAN happen refers to the condensate where warm, humid, air is cooled
and the cooled air releases moisture.

The way an air conditioning SYSTEM often works - at least around here - is
to capture this water and drain it into the house sanitary sewer system. But
that drain can get clogged. Manufacturer's know this and almost always
install a pan beneath the condensing unit to catch the water that can't make
it down the house drain. This pan, in turn, has a separate drain, usually to
the outside of the house.

In a catastrophic situation, here's the drill:
1. The primary drain (to the house sanitary system) clogs up.
2. Condensation then moves to the fail-safe backup pan.
3. Eventually, this pan/drain combo clogs up and the moisture overflows the
pan.
4. If the condensing unit/pan is in the attic... goll-eey what a mess!

Well, what causes the clogs and how do you fix/prevent it?

The "clog" is almost always a big blob of algae. It's quite soft and can be
removed by air pressure (just blow down the pipe) or a snake. Prevention is
almost as easy. Here's how.

At the top of the condensing unit, just before the ductwork begins branching
out, drill a 1/2" hole. At the start of each a/c season, pour a cup of
household bleach into the hole (a funnel helps). Plug the hole with a cork
or duct tape. The bleach kills the algae/fungi/mold/mushrooms or whatever is
growing in the pipe.

This latter is one of the easiest DIY jobs.

Good luck.