Converting ice box to refrigerator

[patrickkidd]

One of the previous owners of my Catalina 30 installed a mini fridge unit in the ice box. The compressor and evaporator are in the port lazarette. The system was working fine for a while but I think it has a leak in it, and it never really gets very cold. I bought a 134a can and pressure gauge to refill the refrigerant which helped, but I'm not expert and the performance still seems sub-par. For what it's worth, the low-pressure side reads about 11psi, there is an audible sound of liquid in the cooling element within the ice box, and the compressor never cycles down.

Anyway, it would be great to fix this unit since it's all built in and I know that they are serviceable (not to mention that I'm on a budget).

But I'm curious what other people have done to convert the C30 ice box to a real refrigerator? I practically live on this boat and the unit needs to run 24/7. This current setup only runs on shore power (which is a bummer) and I know dropping $1000 at West Marine on an AC/DC unit may work although that's a lot of money I'm not aware of the logistics of getting them to fit.

Thoughts? Ideas?

Thanks!

 

[kloudie1]

some things I don't know.. Is it verified to use 134a in the unit? older units might be F-12 or F-22.. Somewhere the tags should point you to the correct refrigerant.. If indeed 134a, then it should be showing around 30 psi on the "low" side..
Check out this web site for some tips and guidelines on servicing the little dear.. http://www.kollmann-marine.com/

 

[patrickkidd]

That's right, it's 134a for this one, it says so on the sticker though it's too small to read in the photo. Are you sure about 30psi? Most sites I've read say 3-5 psi on the low side. Although I've never found official specs for my compressor, the Sanyo C-QN43L2A: http://m.artisantg.com/PLC/60841-25/Sanyo_C_QN43L2A_Compressor.

 

[kloudie1]

Sorry, Patrick.. 30 is too high..I was thinking higher temp stuff.. For 134a, undiluted by air and in a mechanically sound unit, 3-5 PSI is minus 2 to minus 6 degrees F .. probably too low for a refrige.. Somewhere between 10 and 20 is probably more appropriate .. You can look at the evaporator and watch the frost line.. it should frost about 95% of the evaporator .. 10 psi is around 8 F and 20 psi is around 20F.. the squishing sound is the 134a flashing into gas, so that is normal..

 

[alexco38]

I need to line the inside of the ice box with 1" foam board covered with self adhesive foil (furnace duct wrap) to make it cool enough. Those boat ice box isn't well insulated.

 

[patrickkidd]

Sorry, Patrick.. 30 is too high..I was thinking higher temp stuff.. For 134a, undiluted by air and in a mechanically sound unit, 3-5 PSI is minus 2 to minus 6 degrees F .. probably too low for a refrige.. Somewhere between 10 and 20 is probably more appropriate .. You can look at the evaporator and watch the frost line.. it should frost about 95% of the evaporator .. 10 psi is around 8 F and 20 psi is around 20F.. the squishing sound is the 134a flashing into gas, so that is normal..

Oh man, I'm really grateful for your responses, I have been really suffering trying to find info on this problem.

So lower psi means colder. Well right now its at about 10-12psi, and at times the evaporator isn't very cold at all but then gets cold again after a bit. The frost line is hard to see since the copper goes through the hull cavity behind the icebox before entering the lazarette, but at times the entire evaporator body feels lightly frosted in the ice box. Do you think there is a possibility that air is getting into the system and keeping it from getting cold enough, especially if there is a possibly leak somewhere? All I did was fill with 134a on the low pressure side and then once had to let some air out because of overfilling. Or is poor insulation other than whatever is there from the factory and a poorly filled gap in the copper tubing entrance enough to keep the temperature high and keep the compressor unit from ever cycling down? Or should it cycle down at all even if running at the proper temperature? Maybe the thermostat is unreliable? Changing the temp setting has no effect on performance.

Thank you so much for your feedback!

 

[kloudie1]

Sounds like ya may have a couple of problems.. one might be air in the system.. Air does not condense at these low pressures so it takes up space and crowds out the refrigerant .. it can cause surges of refrigerant to the evaporator as it travels through the system.. A thorough evacuation is the best way to make sure there is no air in there.. Some other things to check before calling in a vacuum pump would be to be sure the air fins on the condenser are clear all the way through (they look pretty clean in the picture) and the fan is running .. the compressor should be running too.. check all the electrical connections for tightness.. Again, check out the Kollmann site for some hints about what to look for.. Good luck with it, Patrick.

 

[patrickkidd]

So after a bunch of months of limping along with the AC unit I bought a Norcold SCQT-4408-L icebox conversion kit and so far really love it. It's very quiet and hardly has to cycle up after I re-insulated my icebox with an extra 1" of polyurethane and the hatch inflation case with filler foam. It's very easy to install although you should put some good thought into the placement of the components before drilling and bending pipe.

http://www.defender.com/product.jsp?path=-1|2276179|2276204|2276226|2530801&id=2435427