Adding Refrigerant?

Okay, I’m not going to make any claims of being a refrigerator mechanic.  I’m not!

But just a quick post today with a few things I — or more accurately, we — learned about adding refrigerant (aka Freon, although almost none actually use Freon any longer) to a boat’s refrigerator.  Yeah, another of those things you didn’t know you cared about.  Until suddenly you did.

This is not a step-by-step guide to recharging a refrigerator, just some things we learned that weren’t in the books:

  • It also might be the thermostat that has the problem — a quick test for this is to turn the knob to make the temperature cooler and see if the compressor kicks on.  Try this when the compressor is off — as you start turning the knob, the compressor should come on almost immediately.
  • Another possibility is a blown fuse — or a bad breaker.  Trace your wiring to see if there is an inline fuse, then check it if there is one.  You can test breakers with a voltmeter (if you don’t know how, check any boat electrical book such as Calder’s or Don Casey’s — links are to the books on Amazon US).
  • If you do need to add refrigerant (and it’s not because you deliberately let some out for some reason), you have a leak.  The refrigerator is a closed system and the refrigerant doesn’t just disappear.  You need to find the leak (soapy water is the easiest way) and then fix it.  Rescue Tape is a great “temporary fix” on any of the lines or connectors; JB Weld can fix many holes in other locations, but be careful not to restrict the tube with the JB Weld.
  • Most boat refrigeration systems are small and don’t hold that much refrigerant.  It is extremely easy to get too much refrigerant in the system, so that it is over-pressurized and not cooling.  If you just charged it — and aren’t really experienced at it — and it’s not chilling like it should, try letting out just a tad of the refrigerant.
  • Whenever you make a change to the system, either adding or letting out refrigerant, give the system at least an day to settle in before you make another change.
  • If you’re doing extended cruising in remote locations, it’s worth getting a recharge kit if you have refrigeration. You need the hoses, gauges and correct refrigerant along with the owner’s manual or other information on how to do it and what the correct pressure is.  It’s actually not that hard to do if you take it slowly (Dave and I had never done it before we recharged Que Tal‘s system).  FYI, it’s basically the same thing as recharging a car air conditioning system and there are tons of YouTube videos showing how to do it.

Good luck — and you’ll LOVE that cold beer (or whatever) when it’s fixed!

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  • Mike Wilson
    Posted at 23 June 2014 Reply

    Hi Carolyn and Dave,

    The can of refrigerant you have pictured is for auto air conditioners and while it is HFC134a gas there is often an oil charge added to the can. The oil in automotive air conditioners is PAG oil and the oil in your boat system is POE oil. Mixing these two oils is not a good idea and may cause a reaction if moisture has entered the system and will eat the metal evaporator from the inside out. Remember if you have had a leak and the system got below atmospheric then air and thus moisture will have been sucked into the closed system. After fixing the leak is essential to change the filter drier and then warm everything up and vacuum down to 30″ Hg. for an hour or so, depending on the size of the system. Large cold plate systems may require up to 24 hours of vacuuming.

    MexiColder Mike
    Marine Refrigeration Engineer (Dip. Mech./Mar.Eng. U.K:)

    AKA Rescue Refrigeration Mazatlan Sinaloa Mexico

  • Lynn
    Posted at 23 April 2015 Reply

    And if one adds refrigerant, the air in the manifold tube needs to be dealt with, too.
    I highly recommend for excellent info on refrigeration. He wrote a book, but much of the info is on the site, including how to effectively trouble shoot a Danfoss compressor (used in most of the boat refrigeration systems). Also an excellent read if you are making a new refrigeration system. He will also answer questions.

  • Monika
    Posted at 09 June 2016 Reply

    Good luck finding the correct fitting to get the refrigerant from the can into your fridge. Took us over a week to find and get that little valve for our nova cool and that was stateside!

    • Carolyn Shearlock
      Posted at 09 June 2016 Reply

      It actually might be easier in places like Mexico and the islands — we had no problems getting connectors in Mexico and refrigreant was sold many, many places.

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