Blocked AC

Korkie

Korkie

Active Member
Feb 2, 2016
1,331
Leonardtown, MD Potomac River / Chesapeake Bay
Boat Info
2006 340 Sundancer, Garmin 7610, xHD 24 Radar, VV703, SeaStar Hydraulic Steer, Shadow Drive AP
Engines
Mercruiser 496 Mags
Bravo III Drives
Strange occurrence. While winterizing AC system today, went to run antifreeze through AC system as I usually do and couldn't get anything to flow through system. After several attempts, took hoses off pump and intake of coils, no blockage - could blow through very easily. So took hose off discharge of coils - same thing, flows freely. Put it all back together and hooked fresh water hose up the hose that attaches to discharge side of pump and tried again. Water went through and was quite brown when it came out the through hull. It eventually cleared up and I let it run for about 10 minutes and shut down. Ran to store to get a fitting and came back. Went to run antifreeze threw again and same issue. No flow, clogged. Did same thing, both hoses clear and coil is blocked. Just don't understand how blocked again after just a n hour before could run water through easily. Cannot get anything through coils now - water nor air. Anyone experienced this? Is there a way to unclog coils? Was considering Barnical Buster, but unless I can get it to the actual blockage, not sure it would work.
 
Please only post a question once. We all use the "New Posts" and will see the post no matter where you post it. Hopefully the moderator will combine these threads.

MM
 
I do not like how this works, but as the poster you do not see the threads you post until someone replies. If you click "New Posts", right above the list is "Recent Posts", that will show all threads including the threads you posted in.

Hope this helps,

MM
 
So, i usually put my shopvac on outlet of A/C and suck as much water out as i can before winterizing.
Maybe you can suck the clog out...?
 
Kinda tried that directly on the output of the unit, no luck. Hoses are clear, so going use a syringe with a plastic tube and try and suck as much water out of unit as I can and then introduce some barnacle buster the same way and see if that will work. If i can get just a small opening I can let the barnacle buster circulate through the AC unit for a while to give it a good cleaning. That's the plan, we will see how it works out. Any other suggestions are most certainly welcome.
 
When you flush with Barnacle Buster, run it backwards. Start at AC outlet and run back all the way to the pump. Let it run for at least an hour. While waiting, make sure hose from thru hull to pump is clear, also pull pump apart to clean impeller, they are magnetic, and slime will slow them down. Also if you can find a product called ridlyme, it works much better.
 
Thanks. The clog seems to be 100% so to speak. I took the hoses of the unit and they are clear. Can blow through them with little effort. When I tried to force the blockage out with a garden hose, it didn't give at all. Caused the strainer to leak around the seals. It is quite blocked. Weird thing is as mentioned in original post, IK had a steady normal flow of water running through it using my garden hose for like 15+ minutes. The let it sit of about an hour only to return to same problem, totally obstructed. Will try some ridlyme as well if barnacle buster doesn't work. Also, pump head was removed and cleaned at about mid season and is moving a ton of water when not hooked to system. This is just one of those wonderful boating moments that we all must contend with from time to time. Last year it was the duck bills in the head. That was a fun project too, NOT. You all have a wonderful Thanksgiving and thanks for the tips.
 
If you tried to back flush with a garden hose from the discharge and the strainer seal started to leak then the blockage is probably somewhere between the strainer basket and the through hull on the bottom of your boat.
If the boat is in the water, close the seacock and remove the hose that is between the through hull and the strainer to see if you can find your problem. If it isn’t visible there, then the through hull might be blocked on the bottom of the boat.
 
I'm officially confused.

1) The OP posted that when he pressurized the discharge side of the pump with water....the system worked fine and water flowed from the thru-hull.

2) Then, the OP tried to pressure the discharge side of the pump with anti-freeze and the system appeared to be blocked at the coils of the HVAC unit since no antifreeze flowed from the thru-hull.

3) Then the OP back pressurized the system from the thru-hull and the strainer started to leak water.


#1 does not indicate a blockage
#3 does not indicate a blockage but may indicate the sea cock was closed.

That leaves us with #2. I'm frankly suspicious of the pump you are using to pressurize the system. It doesn't seem like it is working properly. Exactly what kind of setup do you have? If you used a garden hose for #1 and #3 then it is definitely your setup.
 
Well, mystery solved. Turns out it was frozen. When running in reverse cycle, the unit got cold enough with the ambient air temp at 36 that it froze the little bit of water I left in it while retrieving the fitting that broke. A little heat and water flowed freely. Never heard of such a thing, but that is what I got from one Cruise Air tech after calling several dealers. So it got barnacle buster as well. All ready for next season.
 
Korkie said:
Well, mystery solved. Turns out it was frozen. When running in reverse cycle, the unit got cold enough with the ambient air temp at 36 that it froze the little bit of water I left in it while retrieving the fitting that broke. A little heat and water flowed freely. Never heard of such a thing, but that is what I got from one Cruise Air tech after calling several dealers. So it got barnacle buster as well. All ready for next season.
Click to expand...

And so ends the saga. Glad it was not a major boat bucks fix. LOL

MM
 
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