Refrigerant Gas Issues.

[OzePete]

Before the ever reliable R12 was virtually banned, we had three refrigerants that covered nearly every system type. R12 was the most common and now sadly replaced with a plethora of dubious brews, the most common being R134a!

A major issue for users of small (micro!) refrigeration systems is system contamination. How often do we see where a boater has a system re-gassed, or an evaporator or compressor replaced etc only to be dogged with further ongoing problems.
These ongoing problems are a direct result of incorrect refrigeration repair proceedures.

The golden rule:
NEVER add gas or re-gas a system without firstly locating and repairing the gas leak, replacing the filter dryer (with a proper 032 or 052 filter dryer, not a spun copper strainer!), and thoroughly evacuating the system from both the low side and the *high side (*if possible).

Only use clean R134a that has NO additives. Many of the disposable cans, that are mostly intended for the auto air con market, have additives in them and should NOT be used. (Check for pure R134a only, no additives!)

Also, if the system had a leak in the evaporator area it is highly likely that it will have *sucked in a lot of moisture which will contaminate the compressor's polyolester oil and is difficult and costly to remove, so best to simply change the compressor oil before evacuating.
*When there is a low side gas leak (like the wet evaporator area), once the gas is lost the system then pulls a vacuum on the leak area sucking in air, moisture and whatever!

'Repairs' that don't follow the above industry recognised practices may 'work' for a time but are doomed to further failure. There are no short cuts if you want a reliable permanent repair.

Cheers OzePete Ozefridge | 12 Volt Refrigeration Systems

[RaymondR]

What is your opinion on the hydrocarbon based refrigerants such as Hichill minus 30.

I am aware of the perception that because they are hydrocarbon based they might present an explosion hazard. However, in view of the small volumes involved, the very low probability of a leak of sufficient rate to achieve a concentration sufficient to ignite and the fact that most of us already live with hydrocarbon burning cooking appliances with a much greater safety hazard potential I tend to the opinion that the level of risk is acceptable.

[OzePete]

Originally Posted by RaymondR

What is your opinion on the hydrocarbon based refrigerants such as Hichill minus 30.

I am aware of the perception that because they are hydrocarbon based they might present an explosion hazard. However, in view of the small volumes involved, the very low probability of a leak of sufficient rate to achieve a concentration sufficient to ignite and the fact that most of us already live with hydrocarbon burning cooking appliances with a much greater safety hazard potential I tend to the opinion that the level of risk is acceptable.

I have to agree Raymond, the flammability issue is rather exaggerated and the LPG brews have merit, but....
Since R12 was banned we have seen LPG (propane / butane) sold as refrigerant under many banners. Where two refrigerants covered all main stream domestic and DC refrigeration, now there are over 100! And there in lies the problem.

The refrigeration industry has been damaged by stupid political decisions, and all to the frustration of the service tech and a huge increase of running and servicing costs to the consumer and to the environment.
Many of the refrigerants that followed R12 have merit, but do we need hundreds of different brands and brews?
When I started as a kid in the refrigeration industry in 1961, R12 was equal to 38 cents trade per LB in 150LB cylinders, now it is over $20.00 per KG here in Oz!

Cheers OzeFridge Ozefridge | 12 Volt Refrigeration Systems

[rgleason]

Peter, How does one change the compressor polyolester oil before evacuating? Is it difficult to do?

I recently had to add 134a, may have to evacuate and add a filter as you suggested and should probably change the oil.

What early signs should I be looking for that I should evacuate? Is it bad to continue running the pump?

[OzePete]

Originally Posted by rgleason

Peter, How does one change the compressor polyolester oil before evacuating? Is it difficult to do?

I recently had to add 134a, may have to evacuate and add a filter as you suggested and should probably change the oil.

What early signs should I be looking for that I should evacuate? Is it bad to continue running the pump?

Hi RG,
The oil in a properly constructed refrigeration system does not deteriorate.
I would not recommend changing oil unless there has been a serious suction side gas leak or there has been unclean work done on the system.
If your system was just a tad light on for gas then certainly don't consider changing the oil.

When R12 was banned here in Oz, we changed the oil in hundreds of these small systems but that was to replace the then mineral oil with synthetic polyolester to allow for R134a use. It is a simple, inexpensive process.
Unfortunately there are no early signs of oil contamination, only by knowing the systems history can you determine if oil change is needed.

Cheers OzePete Ozefridge | 12 Volt Refrigeration Systems

[rgleason]

Peter, I found the Ozi cord for the ozifridge. It has 3 blades and is rated for 250vdc I believe.

I can add a picture if needed. Can I run the ozifrige on 120vdc by cutting the plug and installing a 120vdc US plug?
Don't I have to be careful about keeping + and - the same? What happens if I get it wrong?

Thanks,
I did a full pull down to today, day was cool 65f.
4:00pm at 1c, -25.6ah
7:30pm at 8c, -42 3ah shut off

3.5 hrs, compressor using 5.2 amps, total 17ah. No engine. Voltage was 12.10 to 12.15 most of the draw down. Voltage is back up to 12.32 now after resting for an hour.

The lower blue valve was cold at the end and sweated a little.
Should I bleed just a little?

[OzePete]

Originally Posted by rgleason

Peter, I found the Ozi cord for the ozifridge. It has 3 blades and is rated for 250vdc I believe.

I can add a picture if needed. Can I run the ozifrige on 120vdc by cutting the plug and installing a 120vdc US plug?
Don't I have to be careful about keeping + and - the same? What happens if I get it wrong?

Thanks,
I did a full pull down to today, day was cool 65f.
4:00pm at 1c, -25.6ah
7:30pm at -8c, -42 3ah shut off

3.5 hrs, compressor using 5.2 amps, total 17ah. No engine. Voltage was 12.10 to 12.15 most of the draw down. Voltage is back up to 12.32 now after resting for an hour.

The lower blue valve was cold at the end and sweated a little.
Should I bleed just a little?

Hi Ric,

Yes your system can operate from 110 or 240VAC or 12VDC. The polarity of the AC input is not important, but the active (hot wire I think you call it there!) is brown. If the AC supply is doubtful, it is safer to run on DC only and top up battery with a charger.
Your refreeze times are spot on as you have the larger capacity eutectic plate. A little cold sweating on the suction line as the system gets close to shutting off is ok, don't purge.

Cheers OzePete

[rgleason]

Great. Thanks!

[rgleason]

Now with warmer weather and higher humidity the ozifrige lower, low pressure side seems to be condensing a lot more at -3c and seems to be hung up there and using more volts (about 6v and then 5.9v after letting out some, just 2 twice)I don't want to let too much out, but perhaps I have some moisture in there that is freezing? I've tried turning the unit off to let it warm up then back on. It has reached -7 yesterday. I have not put on the dryer you suggested this spring. When we get back from this cruise I suppose I should do that and do a complete evac? What should I do for the next 2 weeks of cruising?

[rgleason]

Now it has hit -4 and the lower fitting is cool and not sweating as much.

[rgleason]

Because we are under power, I've just put the controls on high so compressor uses full power
I'll see if this causes excessive sweating and freeze.

[SV_Harbinger]

Some what related, but not necessarily to the cruising world, when I was a bubble head I was responsible for the boats (ships) refrigeration plant and was deeply involved in the change over from r12 to 134a and it was a hastle, condensers needed to be changed we had to switch from a TXO to a TXV with all of it's solenoid ecucherments modify the evaporator coils in the chill box, change out the compressors, new oils, new procedures, quite a headache really.

[rgleason]

Today I discovered that running the freshwater pump which augments the condenser cooling really does help in hotter weather particularly with the heat from the engine. Shortly after turning the pump on, the cold and sweating lower low pressure line stopped sweating and felt cool but not cold.
Evidently the condensor coil and fan were not adequate to keep up with the hot pressurized gases and that was affecting the other evap side.