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240 Sig Air Conditioner

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I have a 2003 240 Signature with AC that I can’t get cold air from. How do I troubleshoot this system?  If this was a car AC system, I would say the system just needed a recharge. Is that something I can do myself on the boat?

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Your marine AC system does not use automotive Freon. It either uses R-22 or R-410a. The 22 is not available to the general public, but likely you have 410a, but you need to look for a system labe and confirm before you do anything. Next, understand that the evaporator coil has a link screen, just like your home HVAC system does, so find it and confirm that it is lint free. It's location will be in the fan housing so if you track down where the evaporator fan is, you will find the screen. Next is the evaporator, which is water cooled on a marine AC unit. As it uses sea water, there will be a debris strainer on the suction side of the cooling water pump. This pump is 115 VAC and will be mounted low in the bilge as it is not self priming and needs to be below the water line to maintain a flooded suction condition. Isolate and clean the suction strainer, and now the testing can begin. As soon as you turn on the AC, water circulation should start and you should see discharge water being displaced overboard from a thur-hull fitting just above the water line. You should also hear the compressor start and the top of the seal unit compressor should feel slightly cool, not cold, and not hot. As far as DIY charging goes, the key is accurate test equipment as 410a systems operate at elevated pressures and their charge levels are critical to acceptable performance. Just a touch overcharged or undercharged and they will not preform to capacity. If the charge gets too high or too low they wont run at all as the system safety pressure switches will hold the system out.  I use a digital micro-processor based charging station that calculates both sub-cooling and monitors liquid line pressure in real time. Gone are the days of slapping a can or two into a system and see what happens as it is so easy to overshoot or under shoot and end up with nothing or damage. These systems are also charged in the vapor state which is not typical with the older R-12/R-22 systems.  You will also need the charge tables that  are unique to your particular system. Below is the unit I bought and it works well. The service techs I've talked to really liked the unit, but went back to something more basic as this thing just does not like bouncing around in the back of their service trucks. Mine sits in it's case and gets used a dozen times a year. Not cheap so I take special care of it W

 

https://www.tequipment.net/fieldpiece/hvac-equipment-and-instruments/hvac-manifolds-and-gauges/manifolds-and-gauges/

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Wow, thanks for the guidance. I’ll check out the system myself, but it sounds like I’ll have to find a marine AC specialist for refills. 

Would a dirty/clogged strainer cause the system to blow not so cold air?

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8 hours ago, skim said:

Wow, thanks for the guidance. I’ll check out the system myself, but it sounds like I’ll have to find a marine AC specialist for refills. 

Would a dirty/clogged strainer cause the system to blow not so cold air?

If the strainer is clogged, or the cooling water pump has failed, the compressor will go out on HPF shutdown within a few seconds after starting, hence no cold air. Look for water going over the side after start-up. Should have a good stream running and it should feel about 30 degrees warmer than the sea water. W

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Now that I think about it, I don't think I saw any water coming out of the side when I was running it for about 20 minutes yesterday.  Cleaning the strainer should be straightforward, but is there a good way to test the cooling water pump?

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7 minutes ago, skim said:

Now that I think about it, I don't think I saw any water coming out of the side when I was running it for about 20 minutes yesterday.  Cleaning the strainer should be straightforward, but is there a good way to test the cooling water pump?

If the strainer is clean, and the pump has 115 VAC at it's plug in terminal, then it should be pumping. If not, the next step is to remover the pump discharge hose and hook up a garden hose to it and see if you can flush water through the condenser coil and over the side with the pump disconnected.   W

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Every year I must "burb" my system in order make the water flow. I just open the sea strainer for a second or two, while the system is running. Some years I must do it a few times, this year it worked the first time I turned it on.  

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13 hours ago, Iggy said:

Every year I must "burb" my system in order make the water flow. I just open the sea strainer for a second or two, while the system is running. Some years I must do it a few times, this year it worked the first time I turned it on.  

I had issues with several factory installations seeing exactly what you described. Talked with Annapolis Cruise Air years ago, and they indicated that the installation should include a hose loop in the pump suction. Sounded counter intuitive to me but I tried it and the priming issue went away. A quick look at recommend installation procedures on line shows the loop by a few vendors, but I only see it factory installed on about 30% of the boats I see. There is also a positive displacement alternative pump available that will self prime and does not have to be flooded suction, but it also has a rubber impeller that has to be changed similar to our raw water engine pumps. See these on tight installations which require the pump to be mounted above the waterline.  W

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Thanks for your help guys.  I got the system to work.

  1. The seacock to the pump inlet was inexplicably partially closed for whatever reason, so I opened that up. But that wasn't enough.
  2. I had to clean out the strainer that was gunked up. Again, not enough to get it going.
  3. Finally, I had to burp the system by unscrewing the strainer for a couple seconds while the water was flowing.  This did the trick.

Now the cabin feels like what an airconditioned car would feel like in the Texas heat. It's definitely going to make the summer out at the lake more bearable for the family.  I'm actually quite surprised at how efficient at cooling the system is, given how small it is.

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36 minutes ago, skim said:

Thanks for your help guys.  I got the system to work.

  1. The seacock to the pump inlet was inexplicably partially closed for whatever reason, so I opened that up. But that wasn't enough.
  2. I had to clean out the strainer that was gunked up. Again, not enough to get it going.
  3. Finally, I had to burp the system by unscrewing the strainer for a couple seconds while the water was flowing.  This did the trick.

Now the cabin feels like what an airconditioned car would feel like in the Texas heat. It's definitely going to make the summer out at the lake more bearable for the family.  I'm actually quite surprised at how efficient at cooling the system is, given how small it is.

Its not uncommon to burp it. Good.......

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1 hour ago, skim said:

Thanks for your help guys.  I got the system to work.

  1. The seacock to the pump inlet was inexplicably partially closed for whatever reason, so I opened that up. But that wasn't enough.
  2. I had to clean out the strainer that was gunked up. Again, not enough to get it going.
  3. Finally, I had to burp the system by unscrewing the strainer for a couple seconds while the water was flowing.  This did the trick.

Now the cabin feels like what an airconditioned car would feel like in the Texas heat. It's definitely going to make the summer out at the lake more bearable for the family.  I'm actually quite surprised at how efficient at cooling the system is, given how small it is.

Water cooled condensers are much more efficient. Quieter too.  W

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