A/C "High Pressure" fix

LP can also be the Evap ( thing with the fins) freezing

Yeah that pretty common, plastic bags will get stuck in the inlet but only kill flow when under suction. Tricky. Usually when you open the strainer they will let enough water to flow in but once you start the pump they get sucked in tight

Another increasingly common issue in Florida are little mussel like shells growing in hoses and manifold.

In Jax, all the run-off, pollutants, fertilizers, road trash and old back yards have created a foul similar to Berber carpet with barnacle larva attaching to that. In a month over the best of fresh paint the diver is scrapping instead of wiping the sediment off.
If the boat is not used, that SpeedProp stuff is useless.
When this crap gets into the A/C lines, It's not pretty.
Hot, dark A/C water and HPF errors are everywhere.

I can't complain to much. It keeps a few of us up here busy.

Problem is that normally you only descale the coils

On the johnson 70 I run we were getting reduced flow on some of the ACs because of the discharge lines which run aft to TH that were impossible to reach.

I had to enlarge access panels, and replace the standard seacocks with three way valves so we can hook up a flushing lines to descale the whole thing. Major pita

The other issue is that they die during a haul out and then pile up at fittings when you restart the systems. I had a manifold completely full of the little buggers after the last haul out

We have mixed reactions with the tabs also. Frost the clear acrylic strainer tubes and makes nylon and forspar fittings brittle.
A part of our inspections & service is using a round tollette brush to clean the strainers and shop vac out any silt on the bottoms.. We can see the frosting starting where the bromide tabs were in use.
We had some customers try to use the tabs in sumps and bilges. It does keep them clean but will eat up the bottom plastic on a rule pump in about a month.

Anyone looked at ultrasonic or cathelco type units?

We service a couple of boats up here that do not have Perko / Groco type strainers. All metal without acrylic components. I guess they could be better candidates for bromide tabs.
Of interest an ole Southern Cross MY (last of 8 imported) with pretty stainless strainers. These big shinny assemblys don't seem to foul internally so much. Could be the center fed design, materials or because we work to the owners rotating schedule @ 3 weeks service intervals and all other boats at 4 week.

copper plumbing elbow fittings from Home Depot go into my a/c strainers. No growth.

Hummm, I have heard this before.
AND, I have a box of old brass and a bunch of fouled strainers (MINE).
New test a coming.

Your rite, I read/typed to fast. Thx.
Got lots of solder on copper junk also.
We have lots of strainers, lots of junk, some time.
Just gotta crawl out of other bilges and back into my own.

You mean like a Zeta Rod? http://zetarod.com

Had one on a Marlow once. Seemed to work. But they are expensive as I recall.

Not really:

http://www.cathelco.com/

and

http://www.nrgmarine.com/

Thanks for the clear explanation of steps taken and glad you found the solution, would be super annoying if your new system had a mechanical failure.

Not an unknown phenomenon on yachts and other complicated things