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Old 08-10-2012, 05:44 PM   #1
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Default Cleaning AC Heat Exchanger

Hello again from AZ,
Last month I replaced the compressor on my 98 3200SCR because it continually tripped the HP switch and shut the unit down. It worked well for about a month. Now... its doing the same thing. I am fairly sure its not the compressor and have turned my attention to the possibility of a partially clogged heat exchanger. I have a portable pump that I plan on hooking up to both sides of the exchanger and running clean water in the opposite direction. My questions are.

1. Is there a solution that I should add to assist in cleaning the exchanger? I know not to use acids, but it seems that It would need something to help break up the grime.

2. Is there a way to gain access to the heat exchanger and clean it manually?

3. The water temperature in my lake right now is 93 degrees. While i dont expect the AC to work well, is 93 degrees too hot to achieve enough of a phase exchange to keep the compressor from overheating and tripping the HP switch?

Thanks for the help. Its been very useful this summer.



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Old 08-11-2012, 07:30 PM   #2
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Derek,

I can't answer your cleaning question but I can tell you that even when the water temp on Lake Norman hits the mid 90's and the air temp is close to 100 I can run both units and keep the cabin at 76 during the day. When the sun goes down the AC has not problem of cooling down to 70 where I like it for sleeping. I do clean my filters at least every other month and I clean the coils each spring.
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Old 08-12-2012, 11:44 AM   #3
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i would start by rebuilding the raw water pump that pulls the lake water into the evaporator for cooling.

they are not self priming.

also, there is a micro filter on the face of your coil that you can't see unless you stick your head down there.

pull it off,and replace it. home depot has the replacement for 97 cents.

with a new compressor, the only thing that would make the power trip is an electrical load, so raw water pump, or the a/c fans.

but, before you do that, i would try another extension cord and shore power location.

it might be dirty power, trippin the breaker and not your boat.
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Old 08-23-2012, 09:33 PM   #4
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Thanks for the info fellas.
However, I have tested the shore power with an oscilloscope and am absolutely positive that it is good clean power. The pump seems to pump a sufficient amount of water out. It is commensurate with other boats with similar AC systems. You mentioned that it pulls water to the evaporator for cooling. Dont you mean the condenser? The evap coils seem to be clean and the filter was replaced recently. I cant however seem to find a way to get into the condenser to clean it. Do you know of a hatch or ever heard of anyone doing it? With the hot AZ weather this has rendered my boat near useless. I have ideas circulating in my head but im too afraid to try any of them. I fear i will make it worse.
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Old 08-23-2012, 10:29 PM   #5
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time to call a marine mechanic to put some gauges on it, obviously our lie's and implied brilliance are not helping.....

man's got to know his limitation..... dirty harry
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Old 08-23-2012, 10:54 PM   #6
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Sorry if that came off as harsh. I really meant no offense. I value all of your ideas highly and use this forum a heck of a lot. I just get frustrated...
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Old 08-23-2012, 11:09 PM   #7
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In my manual it says that any lake water over 90 Degrees will make the AC not work efficiently. Here is the excerpt.

3. Seawater temperature too high for cooling or to low for heating.
Seawater temperature will directly affect the a/c units efficiency. This a/c unit can effectively cool your boat in water temperatures up to 90F (32.3C) and heat (if reverse cycle option is installed) in water as low as 40F (4.4C).


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Old 08-27-2012, 04:01 PM   #8
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You can cycle Barnacle Buster through there. What you would need to do is get a 5 gallon bucket. mix the barnacle buster with water as per the instructions. Remove the discharge hose from either the AC unit or from the through hull. Connect a hose to the AC unit or discharge hose (depending on which you removed). Then run teh host into the gallon bucket. Disconnect hose between Sea strainer and AC pump. Connect a hose to the AC pump and stink that in the bucket. Now, turn on the pump. It will draw the water and barnacle buster from the bucket, into the pump up to the AC, then out hte discharge hose and back to the bucket again to make a closed circuit. You'll need to make sure you know how much fluid the system holds, including the hoses so that you can add the correct amount of barnacle buster. One way is to count teh exact number of gallons that fill the bucket. As the level of water in the bucket goes down, continue adding whole gallons until the bucket is close to full and fully recycling. now use the amount of gallons you counted to determine how much barnacle buster you need to add.

You'll need some pH test strips to periodically test the water. Once the level exceeds a certain amount, then flush all the water and start over again. This neds to be recylcing for a couple of hours. You can do the same thing with an external pump, such as a small bilge pump or very small sump pump.

Check out hte Barnacle Buster website, I believe they have a very expensive kit to do this with, though I think you can build your own for much cheaper. They also have the pH strips as well.

I would bet growth on the internal coils is what is actually causing your problem. If not, don't discount simple corrosion on the breaker itself.


http://trac-online.com/pdf/A-C_Small..._Contained.pdf

http://trac-online.com/index.php?pag...mart&Itemid=64
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Old 08-28-2012, 11:49 PM   #9
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Quote:
Originally Posted by Derek in AZ View Post
3. The water temperature in my lake right now is 93 degrees.
What!?!?!?

93 Degrees! That's just incredible! Do things melt when they fall in the water? LOL
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Old 08-29-2012, 04:13 AM   #10
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you could hook a hose upto the raw water pump, and try running cooler water thru to see if's that your problem.

But i don't think the water is 93 degrees 3'6" deep. submariners call it thermo layers...
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