AC won't prime

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PhilR

Well-known member
Joined
Feb 3, 2011
Messages
416
Fluid Motion Model
C-28
Vessel Name
TUGALONG
Hey Andrew,
The AC on my 2011 R27 won't draw water ever since I had the boat out on the trailer. I've gone forwards and backwards, even tried sideways. What's the fix?
Thanks, Phil
 
This was Andrew's response on an earlier post

"I have not experienced the priming issue myself including on your boat Darrel. This seems to be happening for people that load and unload off of a trailer. If you are on a trailer then try turning the ac on with the boat backed in the water on the trailer. This will keep the nose high and help with priming. If that doesn't work then I will run the boat up to planing speed and try forcing the water in the scoop, and it usually primes by then. Let me know if that works for you!"

http://www.tugnuts.com/viewtopic.php?f=6&t=1392&p=10284&hilit=prime#p10284

Hope this helps
 
I am not familiar witht he R29 but the difficulty of priming the AC seawater pump on the R25 is well known by those that own one. If you check the website for the Dominec pump that was supplied with our earlier boats you see that the installation instructions call for 2 feet of suction head at the pump inlet. This is not possible with our boats. Our installation only allows a few inches of static head at the pump inlet which is not sufficent to fill the long run of hose and purge the air. This and the log run of hose from the pump to the AC unit causes the poor self priming of pump. The limited head appears enough to support normal operation but is not enough to allow purging all the air. Therefore once primed the pump will not be a problem until the next time you take the boat out of the water. My boat was built in Dec 2007 and it has failed to initially prime every time I have launched the boat. Installation location of newer boats may have solved this problem????

My pump appears to not be damaged by running dry for short periods (but the AC unit will soon trip due to hot gas). You can either attempt several times to restart the system (which could shorten the life of the unit) or loosen the suction hose on the AC seawater pump with hull valve open to bleed enough water to flow and purge air. Then when you start the pump it will self prime. I installed a "tee" on my suchion hose just before the pump inlet. It has a small threaded cap on it which I can remove to vent the suction. An added feature is that you can also connect a water hose to the tee to allow flushing.
 
Thanks for the suggestions. My boat is a 2011. How long does it take the factory to solve a problem that's obviously been around for a few years at least.....rather annoying!
 
Cut the hose running to the AC...
Install a Shut OFF Valve + a TEE, to put the hose back together with the shut off valve on the intake side of the TEE...
The open port on the TEE will have another Shut Off Valve in it and be hosed over to the raw water wash down... The raw connection can be another TEE in the raw water output line, or a quick disconnect in the cockpit...
To prime the AC intake hose you close the cutoff valve on the AC intake TEE, open the valve on the hose to the raw water wash down, and then run the raw water pump to purge the the air through the AC... Now turn on the AC..
Once the AC is running you open the cut off valve in the AC intake line (strainer end) so the AC can now pull sea water through the TEE, close the valve between the raw water pump and the TEE on the AC intake, and then shut off the raw water pump...
Probably will only have to do this once each time you launch off the trailer with the system remaining primed after that. - so a quick disconnect for the raw water wash down will not be a burden compared to putting in a permanent TEE.. When it is all plumbed up, priming the AC will take mere seconds...
 
Thanks guys, the additional plumbing sounds like the fix.
 
Don't be so hard on the factory. A major part of the problem with our boats is that we have a unique design with so many desired features not normally found on other boat this size. Think about the onboard diesel genset, large cabin, head, marine (water cooled) AC, thrusters, inboard diesel, very long cruising range on a boat 25 feet long which only draws 26 inches of depth. There is no way to locate the AC seawater pump low enough to self prime instantly. I will have to give Ranger credit for trying to use quality materials at a price which allows someone other than Bill Gates to buy thier product. I tell myself this every time I try to flex my stiff, worn out, 60 year old body into position to reach all those wonderfull components that require modification, service or routine maintenance.
 
Denny-O's modification would work better than mine but I do not have a washdown system. I thought about that mod but I don't fish and since my boat stays mostly on the relatively clean Tennessee River I never invested in that addition.

If someone has washdown I would strongly suggest addition of his design.
 
Bill, you can still put in a Tee and the pair of shut off valves in yours... Instead of plumbing to the wash down, bring the "flush" port hose of the TEE up to the cockpit with enough length to rise a couple of feet above the deck... With a funnel you can pour water into the hose to purge the air out of the AC pump... Switch the valves back to normal and it should start right up....

My TEE is set up with a hose bib so and I have a short hose with double males to hook up to the wash down (used hose from a washing machine - man, I am giving away all my secrets 😉 )... This also makes me able to can run the AC here at the farm using well water before putting the boat in the shed... Takes a hefty flow of water, btw... The hens take delight in wading through the puddles....
 
Release the hose clamp on the discharge side of the pump. Then slide a small screw driver between the hose and the barb. Turn on the unit and this will bleed off the air trapped in the pump. You will splash a little water as it vents. Sounds hokey but it works.

Pat, Ladybug Too
 
Thanks Ladybug...sounds like a quick and easy fix.
 
I agree with Ladybug. I have had more success on the discharge side of the pump using the exact same method described. I am planning on installing a T and valve to make it easier. Make sure you check your filter first though. It will clog up with sea grass and other water things and stop the flow.
 
I'm still having problems. I disconnected the hose that is between the strainer and the pump, at the strainer end. Water came gushing out. Reconnected and tried. No luck. Still no water going thru the system with "HPF" on the display. What's the next likely culprit...the pump?

Phil
 
Phil, I'm not sure how to parse your last post...

Have you taken the AC hose off the thru hull intake (port side of motor on the hull bottom, on a 25) and using dock water forced a flow through the AC unit and out the discharge flushing the entire system - And proving that the hoses are not clogged or kinked?

I blew a chunk of something out of mine one time...
 
denny-o, When I disconnected the line between the ac pump and the strainer, it was full of water that seemed to be under pressure which suggests that something between the pump and the ac unit is blocking the flow. When I'm back at the boat this weekend, I'll have more time to work on it. My boat "lives" in a glass clear, pure water lake with very little debris available to be drawn into the system.

Phil
 
Phil,

When you initially turn on the AC and prior to the HPF code can you hear the pump run? If you are not sure, loosen the clamps on the pump discharge. Turn the AC off if HPF is displayed wait a few seconds and then turn AC on and go back and remove the pump discharge hose. If the pump is working there will be a strong pressurized flow of water much different than just removing the hose with the pump off and the sea cock open. If the pump runs and then gets very hot to the touch and shuts down there is a thermal switch that prevents the pump from starting until it cools down. My experience with the flashing is HPF code on the AC control panel has been associated with a blocked strainer, a closed thru hull 😳 , or a loss of prime from hauling the boat. I have always been able to prime it back by removing the discharge hose with an open thru hull and let the water flow a little and reconnect.

If the pump does run and discharges water try to remove the hose going from the pump to the compressor, at the compressor end and see what kind of water flow you have. If there is a strong flow then the block is in the unit or the discharge side of the unit. Start trouble shooting from there.

Hope this helps.

Frank

Ainokea
R25
 
Make sure the pump is actually running. Ours did not due to the power cord to the pump being severed. Also when used for heat, the HPF code will not come on if water stops as it does when used for cooling.

Heading South to avoid winterizing!
 
Problem solved. The pump was not starting. Took it apart and put it back together and now it works...magic!
 
My suggestion only works on the discharge side of the pump. The reason you get a pressure release on the suction side is that the pump has presurized the air trapped in the discharge loop. Pat (Ladybug Too)
 
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