DIY R134 Charge ?

[Richard Kollmann]

SV Escape Plan, so far the advice give is incorrect and if followed will do more harm to your system than good. Your system when properly serviced will contain a precise amount of refrigerant by weight. If you check the information plate on condensing unit the volume of refrigerant will be listed in grams or ounces. If refrigerant is over or under this amount by ½ ounce performance will suffer. Contamination of air from an un-purged gauge set will also affect performance. Moist air added will block refrigerant flow and if a very small drop inters capillary tube flow will be controlled to prevent low box temperatures. The tiny dryer on that unit will not absorb any additional moisture you carelessly add. The noise you hear is refrigerant and oil being ejected from capillary tube and has no meaning for you other than there is some flow within the circuit.

The first place to start is why do you think this system is low on refrigerant? Is it drawing less amperage which would be a sign of low refrigerant? Is frost not present on 100% of evaporator’s surface? These are the signs of low on refrigerant. Compressor running too long or box doesn’t get cold enough can be a performance problem caused by poor condenser super cooling; fan not running, condenser coil dirty, air interring condenser is too warm, insulation has moisture in it or lid seal is allowing air infiltration into box.

If you confirm that evaporators surface is not completely covered with frost and there is no frost on lines outside refrigerated area and amperage is less than normal it is safe to add refrigerant. If evaporator has frost covering ½ of it’s surface one or two ounces of refrigerant is all that is needed. Slightly less refrigerant is always better than too much refrigerant on these delicate units.

Grunert used 134a refrigerant in their units with BD3 and the newer variable speed compressors. The older BD3 air cooled models draw 5 amps of current until evaporator plate is first frosted over, then amperage will drop to 4 ½ amps as plate gets colder. BD35 and BD50 compressor amperage will vary depending on compressor speed but frost line will allow you to service most any small cap tube system.

If you research servicing refrigerant on my web forum you will fined complete instruction on servicing your unit and tools needed.

[svcambria]

The Danfoss compressors usually have a Shroeder valve (looks like a bicycle tube valve) on the low pressure side. It is to this that you would connect a manometer (reefer gauge). If it doesn't have a valve, you will have to hire someone to remove the end cap on its small tube and re-place it with a valve (unless you want to try silver soldering). The refrigerent is lost doing this, can't be helped; also you can't introduce die into the system (to detect leaks) unless you have this valve.
First tho I would check the LED troubleshooting light which should be on your unit (if i is new enough) and see if it flashes, and what the number of flashes in the group are, and correlate that with the data sheet for Danfoss compressors. Secondly check the water circulation and water pump (you don't mention if you have water cooling as well as air). Check and see if the air cooling fan is working. And check the thermostat by removing one of the wires at the control panel (the little black box by the compressor) to see if it is stuck (if the unit turns off, you have a Tstat problem). All these are much easier to do than fiddling with the freon which in a closed system you should (ideally) not need.
Lastly, can you even buy R 134a? Kinda thought that was sold only to refrigeration specialists. It's super common in Mexico but I thought restricted in the US.
Note: you can top the system up with gas and it will work just fine unless you lost oil - which is really hard to do. And you should purge the manometer hoses by running a little bit of refrigerant thru them while screwing the connections down on the compressor.

[SoonerSailor]

R134a is an azeotropic refrigerant and is not a mix of gases so a unit can be charged with gas or liquid phases. Safest is to do a gas phase charge, even if slower.

R134a can also be bought at almost any automobile parts store without evidence of certification. However, keep in mind that it is a very stable greenhouse gas, more potent than CO2 and more stable than methane so should not be vented to the atmosphere.

Pay attention to Richard Kollman. He is The Expert.

[SV Demeter]

Thanks guys for all the help here. I have not gotten to the unit since last week but am going at it this week.

Heres the problem I am having. The unit runs, pumps water when the water switch is turns on. Fan runs too. No led errors are displayed. I was getting one blink for low voltage but fixed that. The evaporator frosts over fully and pretty quickly. The unit runs and pulls down the temp int he ice box well. The problem(s) are these:

1. The unit after running for 2 days does not shut down or cycle. It just keeps running, and appears to be pulling closer to 6.5-7amps.

2. The refrigerant line on the suction side ices up. There is a coupling at the compressor where the precharged lines for the evaporator connect. This is where it is icing up a lot. Probabyl 3/4" of ice. This line is insulated jast after the coulpling at at several spots the insualtion has been torn a little and there is ice there too.

I have not messed with the freon yet and was planning to put a gauge set on the high and low side before doing anything else. But now I am thinking it may be a t-stat issue? How would that affect the icing thought? It seems to me like because it is cooling the evaporator fully and quickly that there should not be a freon/charge issue but the icing has me concerned.

Where can I find the correct pressure readings for this unit? I want to know what I should be seeing on the high and low sides.

How can I test teh t-stat? Someone suggested unplugging one of the wires from it while the unit is running and if that shuts the unit down then I have a bad t-stat. Did I read that correctly?

Thanks again to all.

[Jetexas]

The ice that's building up is the condensation that should be running down and draining off. Here's a site, which has to do with AC units icing up, but it's the same concept as with your refrigerator.

Air Conditioning Cooling Coil or Evaporator Coil Ice-up, Icing Causes, Problems &amp: Repairs

Here's the causes it lists for icing:
But if the air flow is too slow across the cooling coil or if the refrigerant is not being metered properly into the cooling coil, or if the refrigerant charge is too low, the condensate on the coil surface can form frost and may build up into a coil icing problem or frost may appear on the cooling coil's refrigerant suction line.

I assume there's a fan blowing across the coil somewhere. I'd check to make sure it works. Then I'd check your refrigerant level. I think it quits cycling after a few days because your system freezes up.

[SV Demeter]

The fan definately works and is clean. I would like to check the refrigerant charge and have a gauge set but I do not know what the values I should be looking for on the high and low side should be.

[Richard Kollmann]

What ever You do DO NOT CONNECT GAUGES TO THIS SYSTEM.
First describe your unit; Compressor Model, What evaporator and its size?, What brand or who designed it? Also need history of maintenance on this system.

If your unit has a Danfoss 12/24 volt BD2.5, BD3, BD35 BD50 compressor and frost covers evaporator and amperage of 6.5 amps there is defiantly plenty of refrigerant in system. The question is does it have too much refrigerant.

Thermostat stuck is not your problem either as compressor runs longer evaporator low pressure and temperature will drop reducing frost outside of refrigerated area on a conventionally designed system.

When I have enough information on your system I will instruct you on how to fine tune it using non destructive means.

[s/v Beth]

This is not beyond you doing this- but there is alot of learning to be done, it may be simplier just to have the refrig guy do it. I put in a new danfoss and R134 from what was a R12 system. I had to learn to 1. use silver soder effectively. 2. Use a vacuum pump overnight with guages, check for any leaks and then use the guages to place the 134a. The forum is both right and wrong on the 134a. It is semi-restricted. You can buy it for recharging your car, but the connector is not right to place on your refrig. system- for that you need a HVAC sized tank, and that is restricted.
The bottom line is that I was on the phone to my buddy that was HVAC and we worked on it with him telling me what to do and what pressures were right and the low pressure and high pressure sides, and I did what he told me to do. It isn't hard but it is different. I would trust Mr. Kollmann- and offer to pay him for his time. Believe me, it is much cheaper to have a good HVAC in your corner than to try to do this without any advice.

[Jetexas]

I'd say just go get can of freon and add about 5 psi. See if there's any change in the system. If no improvement after a day or so, add another 5 psi.

If still no improvement, bleed the 10 psi back off and call a service tech.

This is terrible advice because:
A) You're blindly adding freon without vacuuming the system
B) You're supposed to recapture the freon when you bleed it back out of the system

However, it's a very small expense to see if low freon is indeed your problem. Topping off the system could give you another year or two of service before you have problems again.

You can also put soapy water on the hoses to see if you get any bubbles, which would indicate a leak.

[SV Demeter]

My continued thanks to all, especially Mr. Kollman. I have been to and joined your forum and have already found great info!

I will not connect gauges at this stage then. The unit I have is a Grunert Polar Mate. It is both water and air cooled. I am not certain of the model numbers but I believe the evapoator is the large horizontal model. I have recently bought this boat and have no info on the servicing history. It is a 12 volt system and appears to be drawing 6+ amps at start up. Have to look closer at what else may have been on but I think it could be drawing as much as 8 amps on start up. I left it running for a day at the dock with the shorepower off and it pulled something like 130 amps out of the batteries and never shut down. It had already run for 24 hours with the battery charger plugged in prior to this.

I have contacted Ocean Options here in Annapolis to look at the unit but they told me last week I was looking at a 3 week wait.

I dont want to screw this thing up and am VERY reluctant to touch the refrigerant connections. I have a friend who is a commercial/Residential HVAC tech and was hoping to get him on board but that may be tough too as we both work too much...

I can get specific model numbers this eve when I go to the boat. I believe I have mentioned the 2 specific concerns but I reiterate:

1. The unit never cycles, just runs and runs and runs. Pulls box down plenty cold. Evaporator appears to be fully frosted. But after 48 hours of running it should cycle.

2. Suction side line ices up. Where there is insulation this line does not ice up. Where there are small tears in the insulation ice develops. Where this line in connected at the compressor heavy ice develops on the coupling itself.

Could this then be too much refrigerant? It is an R-134 unit. I do not get any error codes on the LED light.

[Richard Kollmann]

Newt, I do not except payment for advice. In the last 25 years of working with boat refrigeration and before retiring from this business I rarely charged for service calls. Now retired for the second time I still support my books on boat refrigeration by explaining new trend and detail not explained in any books. What most boaters misunderstand is there are no two boat refrigerators and their problems the same. The best advice I can give anyone is always do nondestructive testing first and avoid even good faith destructive testing until problem area is clearly defined.

[Richard Kollmann]

SV Escape Plan Yes, your Polar Mate unit has too much refrigerant if the evaporator is Grunert's standard aluminum evaporator. I will not need additional info. The overcharge of your unit is confirmed by high amperage and refrigerant phase change occurring in line after standard aluminum evaporator. There are three different series of Polar Mate units the first one was in a completely closed box with servicing connections on end of box. The second generation unit’s picture can be seen at http://www.marinespecialists.com/marineairsystems/manuals/polar_mate/index.htm This one Does not have a Danfoss compressor.
The third generation Picture fond here http://www.dometic.com/enus/Americas/USA/Marine/Cooling-Kits/Refrigeration/?productdataid=87270 is the current model.

All three models of Polar Mates have a servicing fitting on low pressure (suction) side for adjusting refrigerant volume. Because your unit’s problem is a slight overcharge condition of maybe one ounce of refrigerant the best solution is a controlled bleed off. I do not believe this would be considered by EPA as venting.

Procedure for fine tuning your system.
1. With compressor turned off depress servicing low pressure valve core for three seconds. Then put leak proof cap back on .
Start compressor and let it run for more twenty minutes check amperage and frost on return line I do not know which compressor you have or rpm of compressor so amperage above 6.5 is still too high after 10 minutes running. Frost on return line should not extend on bare copper return line outside refrigerator for more than a few inches.
2. If unit still has too much refrigerant Stop compressor wait 5 minutes and let out refrigerant for 2 seconds repeating bleed process again. Frost line will be the indicator of correct refrigerant charge on this.

Repeat these bleed steps till Frost cover remains over 95% to 100% of evaporator’s surface area and there is little or no frost outside refrigerator on line back to compressor.
The secret to lowering refrigerant volume is to take your time and do it in steps because if you remove too much then 134a will need to be added. Replacing leak proof cap and running more than 20 minutes is very important. Also having unit turned off is important and waiting 5 minutes for pressure to equalize before bleeding out more refrigerant is important

Correct refrigerant volume of a capillary tube system like yours will always depend on condenser’s cooling medium’s temperature. Water cooling up north requires more refrigerant and warm climates require less refrigerant. I would check refrigerant adjustment on air only for one hour and then again on water only cooling before final fine tuning of refrigerant volume.

[Chief Engineer]

Call Woody Sherrod...........Period.

I can give you another name if you PM me.

[SV Demeter]

Mr. Kollman thank you very much for you help here. I will give your suggestions a try this evening. My unit is in fact the second generation model you posted a link for.

A few questions if you dont mind. Im curious about your comment that "This one Does not have a Danfoss compressor." I thought all three versions were Danfoss? When you say depress the servicing low pressure valve I assume you mean the schrader type valve labled suction? Lastly I understand your instructions to be to run the unit without the water pump on, just air cooling at first? You then say to run it on water cooling only? I am not sure I can do this as I think I only have a control for the water pump and the fan always runs.

We bought the boat in RI and have since sailed it home (annapolis) I wonder if the cooler climate up north is why it was overcharged although it had issues up there as well. Voltage drop was shutting it down but I have replaced the wire and better connections so that is not a problem. Thanks agian will report back tomorrow on results!

Thanks Chief Im going to give Mr. Kollmans suggestion a try first and if not successfull I will get in touch.

[GordMay]

Originally Posted by Chief Engineer

Call Woody Sherrod...

I don't know Woody Sherrod
TEL: 410-752-2870
SHERROD Marine
PO Box 27112, Baltimore, MD 21230
1473 Stevenson Street, Baltimore, Maryland, 21230
Tel: (410) 752-2870
Fax: (410) 752-2840
woodysherrod@aol.com

http://www.dometic.com/9bd1c58d-1419...29faf296.fodoc