no discharge water from mermaid AC

Good day all
I am asking for my friend Frank, who has a problem with his AC.
I'm trying to resolve a glitch with Frank's 12K Mermaid AC. It has no water discharged overboard when it runs.
The 12 volt water pump works well with lots of water being pumped into the bottom pipe of the AC unit, but there is no water coming out of the top pipe of the unit, then overboard. Is there a valve within the pipe that is not opening? I even tried a 'backwash' by reversing the pipes, with no luck. I tried mermaids web site, with no luck and have sent them an, as yet un-responded-to email.
Any thoughts would be appreciated.
Sailor John

No valve is seawater side of AC unit. Try shooting water through unit with garden hose. Pump might have a problem where it not providing sufficient pressure. Mud dobbers might have plugged up your overboard fitting. Open up system in various places and shoot through with garden hose to verify all parts of the path are clear.

Unusual to have a 12v pump. Are you sure? Most are 120Vac. And the pumps do go bad.

Thanks Ski,
There is good pressure from the pump. (And you are probably right about it being 110, not 12V).
So, we have good pressure from the pump into the AC's metal pipe, zero at the discharge on top of the AC. If there is no valve in the pipe, I might be ok to try a sort of 'fish' through, to poke a hole in any gunk that may have developed. Mud wasps are in the area, so who knows. Good info thanks!
Stay tuned.
Sailor John

Try the garden hose, but reverse the flow/direction. If the blockage is at the inlet, by jetting water into the outlet of the unit, it may be easier to dislodge. Using the garden hose also makes less of a mess with fresh water.

Larry M said:

Try the garden hose, but reverse the flow/direction. If the blockage is at the inlet, by jetting water into the outlet of the unit, it may be easier to dislodge. Using the garden hose also makes less of a mess with fresh water.

Click to expand...

Yes, reverse the flow with the garden hose but disconnect the hose from the inlet of the AC unit first.

After an eventful journey is often air in the serpentine but since no water circulates the compressor turns off due to overheat. I let the pump with an extra switch circulate the water-two-three minutes before the air conditioner is turned on.
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Norbert

If ac has been left running A LOT (e.g., Florida), coils can build up mineral deposits. The hotter it gets from reduced flow, the faster the deposits form. I guess this could continue until it blocks completely, but before that the Mermaid should trip on high condenser pressure (little red button). Never seen one blocked all the way, but I don't mess with these things much. I do own two, so I know about the little red button.

I did put a manual over ride switch on mine so in rough conditions the sea water pump runs continuous. Prior to that I was having trouble with pump getting air loaded. I didn't plumb that pump in the most optimal way. If it does air load, I can reprime it without having to turn on the ac's and hurry to reprime before they trip!!

Try compressed air through the AC in either direction, my bet is there isn't sufficient water pressure or flow from the pump. Mine are a PIA to prime in the beginning of each season. The pumps are not self priming. Once I get them primed they are good until the next haul out.
Bill

Thank you all for your contribution to our resolution.
You know how sometimes things just work themselves out? Well, I visited my friend Frank's boat today, turned on that AC unit and the system worked perfectly. Go figure.
Maybe there was ice in the line, perhaps something else, who knows; but it's working now. I am grateful for small mercies!
I think I will buy a lottery ticket tonight.
My thanks again to all,
Sailor John