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Philsmith32 02-12-2014 04:52 AM

Isotherm frig
Hello all,

My boat has the smallest Isotherm compressor unit - evaporative plate in icebox. Recently the frig has been working a lot more than normal. Thethermostat is on the warmest temp, the fan next to the compressor works and everything else seems ok. Any clues?

jsaronson 02-12-2014 07:38 AM

Re: Isotherm frig
could need to be recharged.

Philsmith32 02-12-2014 07:42 AM

Re: Isotherm frig
Ok, thanks. I can hear the gas going through the tubes in the box. The plate gets nice and cold too. So,I am looking for some other reason eh.

Delta-T 02-12-2014 09:54 AM

Re: Isotherm frig
Ice or frost on the cold plate. But I would look at the evaporator and check that it is clean. I do not know your system. Is it air cooled or water cooled?

Can we get a few more details on the setup and ambient conditions? Where is the condenser located? Where are you getting clean air to cool the condenser? What is the temp of the Ice box? What is the ambient temp and humidity? What was the ambient temp and humidity when you thought it was working correctly? Is there any frost on the ref lines?

I few pictures would be great. (you need 10 posts to be able to post pics)

capta 02-12-2014 05:20 PM

Re: Isotherm frig
There should be a sight glass somewhere in the system. If you see a few bubbles passing, that's OK, but if you see foam, then you have a problem.
Just because you hear gas moving through a system, does not mean it is operating correctly. Losing just a small percentage of the charge can affect performance considerably. If you are going to deal with this yourself, then you need a real shop manual for your system, gauges and gas, but as they rarely require maintenance, it might just be better to get a professional to check things out. And way cheaper in the long run.

jimrafford 02-12-2014 06:48 PM

Re: Isotherm frig
I have 2 isotherm units. Fridge w/ cold plate and freezer w/ evaporator. If there is ice build up on the cold plate the compressor will run more frequently.

ReefMagnet 02-12-2014 07:03 PM

Re: Isotherm frig
Assuming you haven't removed/changed the insulation, it's most probably low on gas or a problem with condenser cooling but have you checked the cooling temperature? It could be a failed thermostat. My fridge at home has the same problem. I've had it plugged into an external temperature controller for the last couple of years. One day I'll get around to fixing it.

Having said that, my fridge guy was telling me that the seals on the connectors (the ones where you join the compressor to the cold plate on installation) begin to fail after a while causing the gas to leak. The fix is to cut them out and re-join with solder. Of course he told me this while doing the job on my fridge!

Delta-T 02-13-2014 09:39 AM

Re: Isotherm frig
There is little you can do your self for this issue other than making sure the cold plate is clear of ice and the condenser coil is clean and free of air obstructions. And the condenser fan is working. Make sure nothing is blocking the air in and out for the condenser and fan. You say it is still cooling, that means you still have refrigerant and system is still under pressure and if you have a refrigerant leak you can test the connections with soapy water like looking for a tire leak, but you can only check this with the system off. With the system running the larger of the two ref lines is suction and the smaller is liquid line. With the system off and let sit for 5 minutes the lines will equalize pressure and you can check for leaks with soapy water.

Philsmith32 02-14-2014 12:31 AM

Re: Isotherm frig
Hey thanks delta.

Delta-T 02-14-2014 07:44 AM

Re: Isotherm frig
How old is the system? How often has it been used in the past? Full time?

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