Refer Compressor Seal- Heal Thyself?

[Michael Jones]

Had the refer guy out today to see why the engine driven system hasn't been cooling. It was out of r12 and he didn't find any leaks. Will come tomorrow to charge system and thinks the seal(s) in the compressor have dried out from lack of use and leaked the r12 and that recharging the system will cause the seal(s) to start sealing again. At least I think I understood that correctly here in MX. Does that sound possible that the seals could have BEEN the problem and that recharging might FIX the problem? Hope so but very unfamiliar with refer systems.

[Richard Kollmann]

It is true that shaft driven compressors will leak if the shaft carbon seal is not wet with oil. When these compressors were first installed on automobiles the owner’s manual advised to run A/C compressor a few seconds every couple of weeks in the winter to keep shaft seal lubricated. Newer cars will automatically run compressor a few revolutions to prevent seal leakage.

Engine Drive boat refrigeration systems have a number of locations where leaks are possible. If the leak is not located quickly it is best to insert ¼ ounce of florescent dye with refrigerant and run system for several hours or days. Dye will travel and leak out with refrigerant and oil. Leak point can now be found using any inexpensive black light.

If, this engine drive system is several years old the seawater condenser may have developed micro size corrosion holes. The easiest way to test interior of condenser for leaks is to remove water hoses and place balloons on condenser tubes for 24 hours. If balloons inflate condenser must be replaced. Warning, plug loose hoses as water sinks boats and do not run system during this test.

[Michael Jones]

Was back on the boat last month and the good news is the r12 was still in the system-completely charged still. However, when I have the refer in the engine driven mode, the compressor will begin to cool for a few minutes - I can see frost on the line connected to the compressor - but shortly afterwards the frost melts. Again, the refer works fine on shore power or the generator but doesn't cool down using the engine system.

Any ideas on why the compressor seems to work briefly, and then not?

[mesquaukee]

The symptoms you are seeing is indicative of moisture in the system.

When you first start it up it runs fine. Gradually the moisture freezes out in the TX valve eventually blocking the flow of refrigerant. No refrigerant flow, no cooling, frost melts. However the TX valve will remain blocked. Turning off the compressor for a period of time will cause the ice to melt.

The dryer should have been changed when the system was refilled. It is good practice to replace the dryer when the gas in a system has leaked out and the dryer has not been changed for a long time.
If there isn’t isolation valves on each side of the dryer have the technician install some, they are around $15.00 each. It will save aggravation and money in the future.

Moisture can get into the system by several ways.
1. It could have been introduced when the system was filled due to inadequate purging of the service gauges.
2. It may seem very odd but moisture very very slowly penetrates the flexible hoses running to the compressor. It is a process driven by partial pressure. Dryers on such systems should be changed every few years due to this.
3. Moisture could have travelled through the seals on the compressor when the gas leaked out.

[Richard Kollmann]

Michael, Frost on line at compressor after start up is common on dual systems like yours. This compressor line frost on a normal system will disappear within a few minutes as the expansion valve begins to regulate refrigerant flow.
Are you saying that after leaving engine drive running holding plates did not freeze solid?

[Michael Jones]

Hmmm. Unfortunately, I cooled the system down initially with shore power before leaving the slip so when I tried the engine system the holding plates were already frozen. All I can say is after running the refer with the engine system for 30-40 minutes the temp had gone up, not down...

Originally Posted by Richard Kollmann

Michael, Frost on line at compressor after start up is common on dual systems like yours. This compressor line frost on a normal system will disappear within a few minutes as the expansion valve begins to regulate refrigerant flow.
Are you saying that after leaving engine drive running holding plates did not freeze solid?

[Joli]

We have a short season here so the system is shut down every fall by closing off the valves isolating the sytem from the compressor. In the spring we check the oil in the compressor and then purge the air out with the 134a that is in the sytem. Seems like we use one or two small cans from the auto store every year to top off the system. Got me where it is going but we have two freezers, and one fridge. It is a cold palte system that seems pretty bullet proof.

Originally Posted by Michael Jones

Had the refer guy out today to see why the engine driven system hasn't been cooling. It was out of r12 and he didn't find any leaks. Will come tomorrow to charge system and thinks the seal(s) in the compressor have dried out from lack of use and leaked the r12 and that recharging the system will cause the seal(s) to start sealing again. At least I think I understood that correctly here in MX. Does that sound possible that the seals could have BEEN the problem and that recharging might FIX the problem? Hope so but very unfamiliar with refer systems.

[Michael Jones]

Originally Posted by Richard Kollmann

Michael, Frost on line at compressor after start up is common on dual systems like yours. This compressor line frost on a normal system will disappear within a few minutes as the expansion valve begins to regulate refrigerant flow.
Are you saying that after leaving engine drive running holding plates did not freeze solid?

I'm getting back to this issue as my return trip to the boat gets closer. So, with regards to the frost on the line at the compressor disappearing, are you saying that the fact that frost initially appears on the line by the compressor when first operating the engine driven system, then, in a few minutes of operation the frost disappears, is not necessarily an indication of a problem, or what the problem is, but rather a normal aspect of the system?
Thanks,
Mike

[Richard Kollmann]

Michael, there are no two engine driven refrigeration systems the same Frost on return line but no frosting of compressor for a few minutes after compressor is turned on is not something to be concerned about.

You said “I tried the engine system, the holding plates were already frozen. All I can say is after running the refer with the engine system for 30-40 minutes the temp had gone up, not down...” This does indicate a problem with refrigerant flow or loss of refrigerant. It is possible for temperature to not get colder when switching from shore power electric system to engine drive but temperature should not get warmer with engine compressor running.

Your system does have some refrigerant in it as indicated by frost on return line after startup. What do you see when looking into engine drive refrigerant sight glass? Is there frost or condensation on engine drive’s expansion valve?, If there is only condensation on valve place a wet hot rag over valve. If refrigerant starts to flow rage will stick (freeze) to valve and in a minute or two rage will fall off. Wet rag test will determine if problem is caused by moisture in refrigerant.

[Michael Jones]

Thanks for staying with me on this Richard but you may have exceeded my competency! What is rage? Is that a typo (range perhaps?). I did a quick googling but didn't see anything connected with refrigeration.

When I was last on the boat and working on this I didn't notice whether or not there was frost on the expansion valve but certainly can check that on my next visit. From the sound of it so far, it seems like moisture in the system might be the problem, is that what you would guess? The system was still holding a full charge of the r12 so it is not that it is out of r12.
Mike

Originally Posted by Richard Kollmann

Michael, there are no two engine driven refrigeration systems the same Frost on return line but no frosting of compressor for a few minutes after compressor is turned on is not something to be concerned about.

You said “I tried the engine system, the holding plates were already frozen. All I can say is after running the refer with the engine system for 30-40 minutes the temp had gone up, not down...” This does indicate a problem with refrigerant flow or loss of refrigerant. It is possible for temperature to not get colder when switching from shore power electric system to engine drive but temperature should not get warmer with engine compressor running.

Your system does have some refrigerant in it as indicated by frost on return line after startup. What do you see when looking into engine drive refrigerant sight glass? Is there frost or condensation on engine drive’s expansion valve?, If there is only condensation on valve place a wet hot rag over valve. If refrigerant starts to flow rage will stick (freeze) to valve and in a minute or two rage will fall off. Wet rag test will determine if problem is caused by moisture in refrigerant.

[colemj]

Hi Michael,

I believe Richard meant "rag" and "rage" was a typo.

Mark

[mesquaukee]

The idea of the hot wet rag is it will thaw out any ice which has formed in the orifice of the expansion valve. Refrigerant will flow which will cool the rag and freeze it onto the expansion valve. The moisture in the refrigerant will then cicurlate back to the expansion valve and once again freeze in the orifice blocking the flow of refrigerant. The valve will warm enough due to reduced cooling or lack of cooling and the frozen rag will warm, thaw and fall off.

[Michael Jones]

Of course! Thanks.

Originally Posted by colemj

Hi Michael,

I believe Richard meant "rag" and "rage" was a typo.

Mark