Air Conditioning Water Blockage

Discussion in 'General Discussion' started by Flytrade, Jul 1, 2020.

  1. Flytrade

    Flytrade Active Member

    Feb 20, 2018
    Bradenton, FL
    2006 320 Sundancer
    Twin 6.2L Mercruiser
    When I turn on my a/c I always check to make sure there is a steady stream of water coming out of the boat. About a month ago there was no water coming out. I took off the hose going from the pump to the a/c and blew through it - sure enough it was clogged. I was able to clear the clog by blowing very hard into the hose. Then everything worked fine.
    A couple weeks later the same thing happened, with the same results.
    Last week I was at a marina and got the a/c going about 3 pm, with water flowing as normal. However, at 1 am the a/c quit, and the impeller on the water pump appeared to have failed. To get a/c for the rest of the night I bypassed the pump with a water hose, and the a/c worked fine after that.
    So now the question is - what could have caused the blockage? Why did the clog reappear at 1 am with the a/c running normally for several hours? Why was I able to clear it?
    My mechanic will be replacing the impeller today, and he is going to run a solution through the system to get rid of algae, etc. I'm not confident that will fix the problem since I don't see how an algae can stop the system once it's working. However, as you can imagine, I don't want to go through this again. Your thoughts would be appreciated.
  2. Jeepers

    Jeepers Member

    Sep 28, 2010
    Atlantic City,NJ
    1989 390ec
    Clean strainer, hose between strainer and thru hull, and clean the thru hull with a wood dowel.
  3. ocgrant

    ocgrant Well-Known Member GOLD Sponsor

    Dec 31, 2006
    Miami / Ft Lauderdale
    H2O Therapy
    2006 Sundancer 48
    Cummins QSC
    I would flush the coil with barnical buster. Second you say the impeller failed? Did it break apart? Was it coming apart and chunks are in your coil? That would be of great concern and would require a back flush. My guess is you have some good chunkage in your coil and the hose pressure is higher that your pump and can blow it out. I would also investigate the strainer and through hull to insure there is no obstruction in supply.
    Keep us posted
  4. bbwhitejr

    bbwhitejr Well-Known Member SILVER Sponsor

    Apr 14, 2013
    Lake Lanier GA
    2007 44DB
    Cummins QSC 8.3s
    Very strange to hear the impeller in an AC pump failed. They are made out of some super tough nylon/plastic and I have never heard of one failing. Usually the motor on the unit gives it up while the little magnetic pump itself is still good. Interested to see what comes of this.

    dtfeld and gmacd81 like this.
  5. Flytrade

    Flytrade Active Member

    Feb 20, 2018
    Bradenton, FL
    2006 320 Sundancer
    Twin 6.2L Mercruiser
    Thank you everyone for your response.
    Here is an update.
    It seems the impeller is not directly connected to the motor shaft - it's turned my a magnet between the two parts. Somehow the impeller froze in position - will not turn.
    I just came back from the boat and wanted to check the water line going into the a/c and out the boat. I blew on it and could feel some resistance, but not enough to stop the water - at least in my opinion.
    My first thought was as mentioned above - barnacle buster. My mechanic said he will do that as part of the fix.
    I'll let you know how that works out.
  6. stephens013

    stephens013 Active Member

    Oct 8, 2009
    Ft Walton Beach, Fl
    2001 510 Sundancer
    1997 400DA Sundancer
    1994 Chalarral 310 Signature
    3196 Cat; 660 PHP
    3116 Cat; 340 PHP

    Had to replace a pump a few years back for similar issues. If it dose come down to that try and get a pump with greater water supply than OEM.
  7. Flytrade

    Flytrade Active Member

    Feb 20, 2018
    Bradenton, FL
    2006 320 Sundancer
    Twin 6.2L Mercruiser
    I checked my owner's manual, and on the back they have a phone number for Cruisair - 804-746-1313.
    I talked to a tech rep and he said the problem is marine growth in the system. He said to use barnacle buster and that should solve the problem. I'll let you know.
    Thanks again for your replies.
  8. crazy diver

    crazy diver Member

    Mar 1, 2019
    2001 380 AC
    Cat 3126 350HP x 2
    Just had barnacle buster flushed through my system. Works much better. Cost was $250.00 per unit x 3... I thought it was a little high for work involved
  9. CaptRonn

    CaptRonn Well-Known Member

    May 25, 2016
    on a large body of water
    1999 Sea Ray 400 Sedan Bridge
    Convert fuel into noise
    High? That was highway robbery. :eek:
  10. dtfeld

    dtfeld Water Contrails GOLD Sponsor

    Jun 5, 2016
    Milton, GA
    410 Sundancer
    Axiom 12 MFD
    Cat 3126 V-Drives
    Once you get it cleared our and running again, try some Bromine tablets in the strainer basket. When we had the boat in Bradenton/Clearwater, the battle to keep the AC lines clear was constant. Not only algae grew in the lines but little mollusks (clams/muscles etc.) would grow in there.
  11. crazy diver

    crazy diver Member

    Mar 1, 2019
    2001 380 AC
    Cat 3126 350HP x 2
    The A/C repairman who ran the barnacle buster through my system claims that the Bromine tablets are very corrosive. He said that the manufacturer did tests and that the Bromine deteriorated the coils. Who knows what to believe?

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