Priming A/C

skolbe

skolbe

Well-Known Member
Oct 3, 2006
3,549
St. Louis, MO
Boat Info
320 Sundancer, Zodiac 290 Wave Inflatable Tohatsu 6HP, Boston Whaler 130 Sport
Engines
350 Mag V-Drive - Kohler 5ecd
When - dewinterizing - the A/C lost it's prime. I usually just take the boat out for a cruise and then the A/C is fine - this is after winterizing. In case that doesn't work - how do others get their A/C to reprime? I have temporary strainer caps for my strainers with hose fittings - I thought of just hooking up the dock hose and turning the water on to run water through the A/C system through the temporary strainer cap. But I do know their is a procedure to gain a prime - but I don't remember it. I believe FC3 - fires up the generator and get's the boat on plane and turns on the A/C - if I misquoted - my apologies FC3.
 
When we took delivery of our boat, it was brand new, the A/C would not prime after almost 30 miles of cruising. When we got to our home dock we were still trying to figure out why it wasn't circulating. Then, the sales guy put is palm over the hole where the water comes out, and after a minute or so, it started working. Not sure why that would work, but it did.
 
Thanks - my fear is that - the boat ride might not prime it.
 
<"...I have temporary strainer caps for my strainers with hose fittings ..."> I don't know what those are so I'll go with what I know to work.

Three way I know of to regain a prime at the dock and what you use depends on the distance from the strainer to the pump and the amount of upward angle from the strainer outlet to the pump.

-- With the A/C on, go into the ER and crack the strainer lid a bit. If the strainer output is only slightly lower than the pump input, often times enough water is forced by pressure from the strainer to the pump to allow the pump to pick up a prime.

-- If that doesn't work, again with the A/C on crack the output hose from the pump. The pressure of the water coming up from intake scoop will prime the pump. Once you have the system primed and running, tighten the clamp. I have never had this method fail and I used it all the time when I rack stored my Regal. I have never had either method fail.

-- The third and easiest is to stick a garden hose in your A/C outlet and turn it on to a low flow (you dont want to damage the system). When the bubbles stop coming out from the bottom of the hull, the system is primed.

HTH.
 
skolbe said:
Thanks - my fear is that - the boat ride might not prime it.
Click to expand...

Let me clarify... our 30 minute cruise was from our dealer's location to our marina. We tried it 2-3 times while puttering through Lake Union, then again while locking through Ballard. Still nothing. We shut it off until we hit the home port.

We have never had a priming issue since....
 
Try forcing water into the outlet via a hose (if you can reach it). Someone told me about that this spring... it worked for me.
 
I've taken an output hose off the pump once to prime, but discovered that is not necessary. Mine always starts on the first try. Just turned my heat on and it's humming away. You have to give it enough time. It sometimes takes a minute before the compressor kicks on and the pump runs.
 
That's what I do Skolbe. Run the genset, start the A/C, and bring the boat up on plane. She usually primes within a minute.

Good excuse to take the boat for a short run after relaunching.

Best regards,
Frank
 
I did the garden hose to the discharge trick on my previous boat. Didn't need much pressure but it took 15 seconds and was good for the season.
 
Running the boat doesn't work for us. I've actually lost a prime by rocking heavily in rough seas.

I loosen the hose clamps after the pump (pump turned off), insert a small tool (awl, small phillips screwdriver) to allow the air to burp out. Tighten hose clamps after water seeps out. System is ready to go (like David said).
 
The loss of prime is due to air trapped within the system.

Your best bet is either take the boat out on a cruise or crack the house at the pump. I like cracking the hose because it seems to be the easiest. I have actually thought about putting in a T fitting in the discharge hose with a small gate valve. I could then purge the system of air without loosening the clamp.

Doug
 
It does happen. The pump is air locked. Bring a dock hose into the bilge. Install a shut off on the hosebib, close the sea cock, remove the raw water intake hose from the sea filter. Place fresh water hose into the sea filter input and wrap with a rag to force most of the water in to the sea filter. Open the shut off at the hose end and allow water to force into the filter pump and to purge the lines.When you have water running through the system, shut off fresh water and remove the hose and quickly re install raw water hose line and clamp.

Start AC at dock or when launched, run ac and watch water cycle. It should be perfect.
 
Running the boat worked great! Brought it up on plane twice and then - fired up the generator and turned it on and - it worked.
 
I trailer my boat so I lose prime all the time. Since I have easy access to the A/C unit (under the forward berth) I added two valves and a tee to the discharge line. The valves allow me to close the line to the through hull and open a line that I suck on (please, let's try and keep it adult). I also added a switch that I can turn on the pump without running the A/C. I turn on the pump, toggle the valves, suck on the line, and when the pump gets primed you'll know it. The tricky part is toggling the valves back to run mode. If you aren't quick enough you get a mouthfull of seawater. No disconnecting from shore for a ride just to prime the pump. Then turn on the A/C and switch the pump back to A/C control. FWIW - Bob
 
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