I've done it myself with them in place using a very strong substance in a spray bottle, it's sold in HVAC specialty suppliers over the counter.

It foams up, you spray it off with a garden hose.

Anytime you remove something you risk damage and you have to recharge the system, that's extra cost.

OTOH, maybe the cleaning they do this way is more thorough.

How do you spray off the cleaner with a garden hose if the air handler is inside the house???

While the AC is running, the refrigerant gas is compressed and circulated, then evaporates and becomes chilled at the evaporator, inside the house.

Air is blown across the evaporator coils and chills the air. If one keeps their air filters clean there's rarely a need to clean the indoor evaporator coils.

When the gas condenses back into a liquid, that releases heat energy (exothermic) and these are the coils that I'm talking about cleaning every year, outdoor coils.

I don't quite understand your system, but if that's the common practice I suppose it's OK.

Here, compressors are outside but air handlers are inside.

Thanks for your input.

Including the system he described in CA.

The compressor outside (shockingly enough) compresses the refrigerant, and then it evaporates inside, within the air handler. Heat pumps use the same concept, but can "run backwards", so that the compressor gets colder and the air handler gets warmer.

I'm not familiar with any A/C system which lets you remove the actual coils. That requires removing all the refrigerant first.

I've been told that "back in the old days", you could remove the fins that were attached to the coils, and thus wash them as you describe. But as efficiency went up, that had to go away. Now the fins are not designed to be removed.

I like to be prepared for the worst; hope for the best.

At worst, you can replace just the air handler without having to replace the compressor, too, right?

Four years ago, I had to replace the compressor due to age, but had to replace the air handler as well as it was no longer compatible (freon versus whatever the new stuff is --- pyron or something???).

They've not come up with yet another type of refrigerant in four years have they???

There's some limitations - you can't use a more powerful compressor, for example. There also may be efficiency reasons to go ahead and upgrade the air handler. (It's the cheap part)

n/t

Is the air handler positioned so that all condensate runs to the drain? If it has settled some, another place may now be the low spot, so condensate collects there.

Also, it's common for there to be two drain pipes these days. That way there's a backup if the main drain gets clogged. You sure you poured the bleach down the only drain?

There's only one drain to my knowledge, which I pour bleach down. If there's another, then I don't know.

I am NOT knowledgeable about this stuff at all. But I've learned that the more you can learn and understand, the better chance you have to keep from being ripped off royally.

Thank you for your help.

Inside the air handler or outside in one of the drain pipe access ports?

It could debris in the port that drains to the line. Can you visually inspect the pan inside the air handler?

Some times algae can build up in the port - that happened to me (you can purchase tablets to prevent algae) A friend had a piece of paper stuck in his drain port(a piece of the label off the furnace)

You could have ice build up. That can be caused by low refrigerant or a couple other reasons.

It's hard to believe your inside coils can be that dirty after 4 years... Unless you are running without a filter. It could be a really dirty filter restricting the airflow which could cause ice and back up.

There's a cap for this purpose.

I change filters regularly and use good quality ones. They blame this on the pets.