Reduced Flow from A/C

J

jrpar

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11343
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After servicing all the raw water strainers and flushing the lines, I'm still seeing a reduced flow through the A/C unit. Pump is good.

Is there any tricks to flushing the lines? Any home-brew concoction that will help??

John
 
A speedometer cable run thru the unit will usually knock loose sludge in the water passages.
 
I ran some Lime Away thru mine then flushed with a hose for about a half hour. Good flow after that.
 
That's a good idea. Also a really large gauge piece of weed wacker string will work.
 
I've had this problem each season I've commissioned the A/C. Strainers clean, seacock open etc.. Turn it on and minimal water drips out the thru-hull. Each time it's happened, I've pulled the intake side from the A/C unit, briefly switched it on at which point I've verified it's pumping plenty of water. Re-attach the intake. Turn it back on and it runs like a champ. Not sure why it happens or why that works but give it a try...
 
flush from a garden hose into the outlets to back flush.

I cant find a pix but one of those really cheap twist nozzles if taken apart yields a long skinny nozzle that fits into the through hulls. The short sweeper nozzle may work as well. I duct tape the hose to a boat pole and stick it into the hull outlets.
 
The backflush via the thru-hull is a standard procedure on my list..
Did the Lime-Away treatment criculate (ie a closed loop or did you just fill the strainer and let it pump thru.??
 
I use an electricians fish tape as a snake. Been able to get through almost all the system with that.
 
Could be crud or build up in pump impeller.
Marsh pumps are magnetic, not shaft driven.
Crud can slow dow the impeller.
Also could be plugged heat exchanger.
Could also be build up on intake scoop.
 
The coils of a A/C compressor need to be "boiled" out from time to time. Especially if it's being run in salt water. Just flushing or snaking them out will not clean the walls of the coils. If after flushing and checking the pump and the strainers the water flow is still low or the system still doesn't seem to cool as well as it did or should then it's past time to boil out the coils.
 
I have a Marine Air system and they recommend flushing the condenser coils with 5% solution of Muratic acid. The coils are brass and not affected by the acid.

Of course double check with the customer service rep for your unit to assure yourself that the process is recommended for your unit.
 
quote:
Originally posted by Capt. Bill1

The coils of a A/C compressor need to be "boiled" out from time to time. Especially if it's being run in salt water. Just flushing or snaking them out will not clean the walls of the coils. If after flushing and checking the pump and the strainers the water flow is still low or the system still doesn't seem to cool as well as it did or should then it's past time to boil out the coils.

Click to expand...


I have heard of a number of ways of doing this. What is your preferred way, Bill? Hopefully the unit can stay in the boat!
 
It is the heat exchanger, not the coils. Coils is what the air blows across.
Most heat exchangers are made out of copper nickel. Brass will pit and corrode faster.
 
Buildup in the coils rarely result in reduced flow but will affect the coil efficiency.

If you actually see reduced flow out the discharge check ;

-the thru hull: I ve seen plastic bags stuck in the TH reducing flow when the pump starts sucking water. Go take a look under the boat
-the short hose between the TH and the strainer especially if there is a 90 deg elbow at the strainer inlet. You can trying pushing a wire thru or may have to disconnect the hose at the strainer inlet
-for an air lock if the pump is improperly installed and you have a high / low point in the hose between the strainer and the pump

Don't get me wrong you still need to descale the system every 2 to 3 years in Fl but it will not explain a fairly sudden flow restriction
 
It has been a gradual decrease over time, but the warm temps spurred growth, so frequency of cleaning strainers & backflushing has been upped..
This unit was installed last July, so there may be enough time for it to accumulate some crud. This isn't an irlock issue..I only get that after hauling and a short back flush thru the discharge purges the air and flow is good..

I'll check the spec's on this unit to see if it can handle the acid..It's a Vector Turbo unit.

John
 
muriatic acid is strong stuff and hard to dispose. i really doubt it would need descaling after such a short time. I've gotten up to 3 years between descalings

i bet on something restricting the flow between the TH and the strainer. that's happened to me many times over the years.
 
I just poured Lime Away into a funnel attached to the pump and turned on the system. As soon as it started to come out the thru hull, I shut off the system and let it sit full of the stuff for about 20 minutes. After that, I connected a garden hose to the line from the pump to the AC and let it flush thru the system for about a half hour. It seemed to have cleaned alot of scale out of the heat exchanger, cooled better after that.
To the OP, how old are the hoses conecting the thru hull to the pump to the AC? If they are old, they could be internally collapsing and blocking flow.
 
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