AC discharge

[Grafunkus]

Grafunkus went in this week!!! Yeah!!! Turned on the generator, because we had it tuned up over the winter, and the ac unit (to create load for the generator) Noticed that there was no water discharge. Fan was blowing. Not that I was worried about actually turning the air conditioning on, there was frost on the docks on Sunday morning. Just wondering, is there a pump that has maybe blown???? Is it an issue if I run the unit without water pumping through it to either cool or heat? Where might the pump be if I have to find it. We have a 1982 33ft Carver 3396 Mariner.

[Viper]

It needs to have water going through it or it won't work. Are you sure the compressor is actually kicking in? The pump won't turn on with just the fan running. It will turn on when the compressor cycles on. If you confirm that the pump is actually running, it may just need to be primed. With the pump running, I just loosen off the screws a bit on the front face. Eventually she will start squirting out water through the pump. When it does that, tighten up the screws and she should pump water. Let us know what kind of pump it is when you find it. It'll be in the engine compartment of under a floor hatch. Did it get winterized?

[Grafunkus]

Viper - to the best of my knowledge it did get winterized (we don't do our own) but I also recall that it didn't pump out water the last time we had it on last summer. I guess I will have to listen more carefully when we turn it on again. My biggest question is - can the fan run without damaging the unit?

[buster53]

Every AC system I've ever seen, the compressor won't run if there is no water pumping through it.
Make sure the thru hull for the pump is open. Don't ask where it is located...you need to get a flashlight and spend some time in the bilge. Locate all thru hulls and identify what they are used for. Find all bilge pumps. Find your water system pump. Find your sump pumps and when you do, clean them out.

Now that you have confirmed your thru hull is open, turn the AC on and adjust the temp either up or down far enough that the compressor turns on. If it turns on and water is pumping you are go to go. If it turns on and no water, it should turn off fairly quickly.
No water...could be a bad pump, blocked thru hull or the pump has lost it's prime.

Yes, the fan will run without water pumping. That is standard operation.

[Viper]

As Buster mentioned, you will need to find the pump and confirm the seacock is open. The pump and compressor are turned on at the same time. The fan operates independently of them and can run all day by itself without damaging anything. Open up the cabinet housing the air conditioning unit, then turn the unit on and set it to high heat setting. When/if the compressor kicks in, you'll know it, it'll sound different. At that time, the pump should turn on. You should hear it operating, and placing your hand on it should indicate whether it's actually running. Depending on the system, if the pump isn't pumping, the compressor will either continue to run or shut down on it's own as pressures go out of range, older units aren't that smart. If the pump is running but isn't pumping water, it either has a broken impeller or it needs to be primed as I described above. The key to priming is that you act fast.

[John Easley]

Since you mentioned it "went in" this week, we can assume it was out of the water for the winter. If that's the case, it probably isn't primed and that is pretty easy to take care of. What the others said: find the seacock and verify it's open. It's most likely in the engine room near the pump. Turn on the a/c or heat and crank it to an extreme temp to encourage the compressor to start. Once the compressor starts, you should hear the raw water pump start. If no water is coming out, the pump will probably need priming. I mean, it could be a defective pump but since it has just been splashed, it's probably best to start with checking the prime. Loosening the hose or screws, as someone else noted, will probably be enough to bleed the air out of the system. The pump will need to be running for that to work. For future ease, you might consider putting a T fitting in the hose coming out of the pump and attach a garden hose bib or some other water valve. It will only take a couple of minutes and a few dollars but it makes bleeding the air out of the system so much easier.

[RGrew176]

On my 3007 the easiest way to prime the seawater pump for the A/C is to take the boat out for a short run. That primes the pump for me.

[buster53]

On my 3007 the easiest way to prime the seawater pump for the A/C is to take the boat out for a short run. That primes the pump for me.

Every boat is different. The sailboat I used to have....I'd lose my prime just running the boat over to the fuel dock and back. Eventually, I learned to close my thru hull before leaving my slip.

[km1125]

Source of the post On my 3007 the easiest way to prime the seawater pump for the A/C is to take the boat out for a short run. That primes the pump for me.

Depends on what type of thru-hull they installed. If you have a scoop, then it works great. If you have a flat intake, not so much (although that also depends on placement on the bottom).

Also depends on how high the circulation pump is and what restrictions (hoses, strainers, etc) are in place between the thru-hull and the pump.

[AaHubb]

A priming method that has worked well for me is to use a wet/dry vacuum at the water discharge port on the side of the hull. You just need to get water to the impeller. The pump can fill the system after that. If the pump is already trying to pull in water this method works quickly.
..Aaron