DIY R134 Charge ?

[Richard Kollmann]

To verify the compressor is or is not a Danfoss unit compare the two pictures web sites I sent with your unit. If your Module looks like the one drawn in http://www.marinespecialists.com/marineairsystems/manuals/polar_mate/index.htm
Picture it is not a Danfoss compressor and Present Grunert tech can not identify it.

Yes, depress suction Schrader valve.


I understand your unit is either air or air and water together. So run unit one hour in fan only configuration and one hour in the other configuration to confirm frost line is about the same. At your present location air and air with water operation should be about the same this time of the year.

Do not try to lower refrigerant to quickly it may take two or three nights to get it right. The slow effort will save you from $400 to the $2000 I have seen spent by others. The one that spent $2000 was on his new Polar Mate installed in New York before his trip down the ICW. Somewhere on my forum you will find his complete story.

[SV Demeter]

The picture attached in your most recent post is my unit. Im very grateful for your help here and hope it works. Will update tomorrow.

I am certainly not interested in putting more than maybe $400 into this system as our longer term refrigeration plans do not involve this unit. We plan to build a new box with a separate freezer. Am still reading and learning and have not yet settled on a refrigeration system for the new box(s). Am leaning towards Frigoboat with a keel cooler but its still early. We plan to liveaboard probably starting in the tropics. Have been thinking of a separate freezer with maybe a spill over door to cool a fridge. Not leaning towards cold plates at this point. Want to be able to run system from Wind and Solar with the occasional engine/gen set battery charge. Also want a system that I can service or better yet that I dont have to mess with! We have a lot of other work to do to this boat though including a full re-wire so I was hoping to just get this unit to work correctly for this summer so we can use the boat and figure out all the things we need to refit.

Thanks again,

Ted

[bene505]

Just a thought... if the wiring was too small, perhaps extra coolant was added to overcome that? (In combination with the more northern sailing ground, of course.)

Regards,
Brad

[SV Demeter]

Ok so I think we may have fixed the fridge! Last night I followed Mr. Kollmans suggestions and bled off some of the charge. I started the unit on its warmest setting with only the air cooling after a 3 second bleeding. The unit was drawing 6.7-6.9 amps at start up at 1900hrs and by 1930 it was down to 5.6amps but there was sill frost on the suction line. I shut it down waited 5 minutes and bled off another 3 seconds. Started the unit up again and got 7.1amps then after 20 minutes down to 5.2amps but still frosting. I repeated this process until I got close to running out of beer making notes of the time and amps. My last run I started the unit at 2224 and it drew 7.2amp initally then in 10 minutes had fallen to 5.5amps and by 2244 (ran out of beer) it was pulling 4.8amps. I shut it down waited and bled off some more. Then at 2255 I started it again with the thermostat at its warmest setting and left the boat with it running. It was pulling 6.9amps at initial start up but dropping quickly. Went home and to bed.

This morning I went to the boat after dropping kids off. The unit was off and there was no frost on the lines. The evaporator was cold and the box temp was 50*. Keep in mind this was at the warmest possible setting. Yeah it cycled! I turned the t-stat up to 4 and the unit kicked on pulling 6.5 amps initially but within a few minutes had dropped to 5.3. I turned off the shore power and went to work. Will see tonight if it is cycling and not icing the suction line.

[DeniseO30]

Maybe the sailors advice applies here SV, "when in doubt let out" lol it seems you have had some luck! One of the reasons DIYers and inexperienced mean wellers should not be adding gas into these little units. OVERCHARGING! Also allot of hvac persons go by the old idea that returning saturated gas cools the compressor, but that would not be true in most refrig units where the comp can get warm even hot to the touch.

For 30 yrs we've used a thing called a "dial a charge" cylinder made by robinaire. I still love that old piece of equipment! but it was never designed for 134. Now of course it's all done with digital scales the whole freon tank sits on.

The problem with really small units is the amount of freon they hold. Many hold well under a lb. the smaller the charge the more critical it is of course.

this the tap valve everyone needs to access sealed units; called a "bullet piercing valve"

but it just amounts to a hole in the tubing that can also leak.

[Richard Kollmann]

SV Escape Plan, I guess I did not make it clear But STOP using amperage reading to adjust refrigerant volume. I wanted you to use amperage readings until 20 minute running time amps were below 6.5 amps from then on frosted areas determine location of refrigerant phase change not amps. Starting amps are of no interest until they are over 7amps. If you let out another 3 seconds of refrigerant you may go to far so stop adjusting now. Running amperage from now on will depend on evaporator’s demand for refrigerant flow. The warmer evaporator the higher amperage, the colder evaporator is the lower amperage reading will be. Actual amperage readings will depend on Super Cooling in condenser and Super Heat in evaporator as refrigerant moves through system. Because you have a odd brand compressor I would guess running amperage after 20 minutes on a warm day will 6 amps and 4 amps before cycling off with thermostat set at mid range.

[SV Demeter]

Thats pretty much what I was doing was mainly providing amps info for reference. During each cycle I was looking for frost on the suction side to retreat back towards the evaporator and I believe i have achieved that while retaining 100% on the evaporator itself. The other problem of the unit not cycling appears to be corrected now as well although this evening will verify that the box temp has been pulled down sufficiently and the unit is cycling on and off.

Hopefully you wont hear any more from me on this one. I will definately be back when I get into designing the new box and separate freezer system though. What do you think about a system using a 12volt frigoboat setup with the keelcooler, a separate freezer box with a thermostatically controlled spill over door providing the cooling to the fridge? We can talk specific dimensions later but what about this sort of set up in general? Perhpas I should post on your forum.

[s/v Beth]

Thank you- I learned quite a bit here on this thread.