Recharging A Fridge With 134a

[cyber-bill]

Just installed a new adler -barbour 100 with a cold plate in my ice box and have the following problem. The unit runs with out cycling and the cold plate only has frost on it at the lower 1/3 after 2 days of running. From what I can gather this is a sign of not enough freon. I have contacted the local repair shop and they are at least 2-1/2 weeks behind right now . At first I thought I could go to the local auto store and buy some 134-a and add some freon to the system, What I found out is that the fitting on the compresser is very small (about a 3/8 dia thread) and does not have the quick dissconnect fitting that is compatable with the hoses that are sold in the auto store. My first idea was to buy a fitting that would marry the auto quick dissconnect to the compresser fitting, but there does not seem to be such a fitting available. Any one with a suggestion would be greatly appreciated. I know you are supposed to be a licensed tech to add freon, but what if you are somewhere in the bahammas far from a repair shop with a fridge full of food.
Bill

 

[SS MAYFLOAT]

Re: Recharging A Fridge With 134a

The fitting your looking for is called a Schrader valve. These are sold at HVAC/R suppliers. Basically it is a 1/4 inch flared fitting with a valve core like a car tire has.

First of all, is this a cap tube system or a TXV system? A way to tell is if there is a receiver tank on the condenser unit. The TXV system is a bit more forgiving for having a bit too much or less refrigerant. Most of these type systems will have a sight glass. These are fairly easy to charge by eliminating the bubbles in the glass. Just make sure you have pruged your charging manifold/hoses before using. Air is a big killer with R134a systems. So with this system you could charge it yourself, but only add an ounce or two at a time.

If it is a cap tube system, it HAS to have the exact amount of freon. The way to tell is if there is a very small tube coming off of the condenser coil going to the cold plate. It will also be paired with the suction line which will be larger. These systems will not have the receiver tank. To recharge a cap tube system the correct way is to recover the existing charge and then evacuate the system. Then using a charging scale or cylinder you must weigh in the exact amount of refrigerant. There should be a indentification lable that specifies the amount the unit holds.

Also if any air gets into the system, the moisture in the air is enough to cause the cap tube to clog up with ice. The cap tube has a very small hole and it doesn't take much to clog. Over charging a cap tube system will cause the suction line to freeze clear back and into the compressor. This is not good and will cause damage if the unit operates for a long period of time.

BTW, you must be certified in the removal and disposal of the refrigerant and not for recharging. So if yours is a cap tube system and you don't have the recovery/reclaim unit, your opening up a can of worms since you need to have the proper evacuation for recharging it.

How much does this unit surpose to hold and are you sure it is R134a. It will also state that on the identa plate.

Hope this helps, just getting up and not fully awake yet.

 

[cyber-bill]

Re: Recharging A Fridge With 134a

Hi SSMAYFLOAT and goodmorning to you. You had mentioned two types of compressors, one thing I know is there is no sight gage on my unit. It seems to be a very simple unit and they call it a air cooled danfoss bd50f high efficiency compressor. there is two quick connect couplings that are used for connection to a remote evaporator that in my case is called a vd-160 and is a cold plate that resides in my ice box. The compressor is supposed to come precharged and after making the connections the system is sealed. I remember seeing a tag on the unit that has the amount of r-134a charge, I am now at home and the tag is one the boat. I think it read something like .16
but I am not sure , I will check it tommorow when I go back to the boat.
Both the cu-100 compressor and the vd-160 evaporater are described on page 911 of the west marine catalog. If you look at the picture of the compressor at the top of the page you can see a brass tube coming out of the top of the compressor with a cap on it. under the cap there is what you describe as a shrader valve, it is threaded about 3/8 in dia and has a valve in it. All the auto hoses have a fitting on the end that is for quick dissconnect, but the valve on my unit is threaded with a male pipe thread. I read a book by a very knowledgeable guy today and he said by law you as a private individual can top off your system when required. But if the system needs evacuation and recharging the feds state it has to be done by a licensed tech. My problem is how do I go from a auto quick dissconnect to the threaded shrader valve that is on my system? There must be some sort of adapter that makes the connection between the two types of fittings.
Thanks for your help, Bill

 

[SS MAYFLOAT]

Re: Recharging A Fridge With 134a

Auto and HVAC/R takes two different certifications. That is why your not able to find an adaptor. If you have an appliance parts store in your area, they should be able to sell you a can of 134 with the right fitting you need. Too bad you don't live close, cause I have quiet a few hoses with the fittings you need.

Once you do get set up to add the charge, let a little come out of the hose to purge the air out of it. Then hook it up to the compressor fitting that comes out of it. Open the valve on the can and count to 3 and close the valve. Give it about 5 or ten minuets to see if the frost moves further down on the evap coil. Be sure that the unit is running before adding the refrigerant. Repeat the process until your evap coil is completely frosted. If you get frost back to the compressor, then it is over charged allowing liquid freon into the suction port of the compressor. This is not good for the compressor.

The quanitity of freon is usually measured in pounds or ounces. Since this is a small unit, I'm thinking it is ounces. BTW, it is a cap tube system. So it is real important to have the correct amount for proper operation. Good Luck,,,,,,,SS

 

[cyber-bill]

Re: Recharging A Fridge With 134a

Hi again SS,
just came home from my boat and I remembered to look for the freon tag that came with the unit. Here is what the tag says total charge 105 grams. By the way this unit was new when I purchased it from a ac place near by, he said this combo was disscontinued a while back . Any way the date it was manufactured was 11 - 7- 2000, Is it possible some of the freon leaked out over the seven years it was in the packing? Also I wanted to ask you about leak detection stuff, I used soapy water but is there something better that can be sprayed on the connections? I will check the appliance repair place tommorow and see if they have the hose I need. I have a boat neighbor that bought the same fridge and cold plate from the same place and his works super.
Thanks, Bill

 

[SS MAYFLOAT]

Re: Recharging A Fridge With 134a

If you have a Grainger in your area, they carry some of the charging equipment.

 

[cyber-bill]

Re: Recharging A Fridge With 134a

Good morning SS,
The local repair shop sent a man to my boat the other day with out my knowing he was there. I don't mind that as I told them my boat was open and they could go any time they wanted to look at the unit. So yesterday I found a note from the repair fellow that stated he topped off the freon and after a half hour of running the cold plate showed frost. Well the cold plate did frost up to with in 1/2" of the top and the line running back to the compressor was also white with frost within a foot of the compressor. It all looked good to me except for one problem even with the thermostat turned down to only 1-1/2 the unit ran continuesly and never cycled at all. The box was 40 degrees at the bottom, this cold plate is supposed to be big enough to make an ice box like mine a freezer (4.5 cubic feet). Seems to me the box should be a lot colder then 40 degrees especially with the unit running continuesly. The repair guy is supposed to get back to me today.
Bill

 

[SS MAYFLOAT]

Re: Recharging A Fridge With 134a

If the heat wave has hit you like it has us, that could be the reason. I noticed in the website where it was advertised that there were two models. One designed for tropical climates that used water to cool the condenser and then the air cooled for moderate temps.

Good to hear that you got it back up. Lets hope the temps stay a bit cooler than they have been. Good Luck,,,,,,,,SS

 

[cyber-bill]

Re: Recharging A Fridge With 134a

Hi SS,
Well it has been two days since my fridge has been serviced by a pro and it has not cycled yet and the frost on the cold plate has dropped from 1/2 inch from the top to half way down the cold plate. Also after he charged the system the copper tube going back to the compressor was covered with ice within a foot of the compressor, and now the frost is a yard from the compressor. I am no expert for sure but this tells me I still have a leak some where and am losing freon. I would have thought the service guy would have checked for leaks before he added more freon. Is it that hard to check for and find leaks if the unit looses freon that quick?
Bill

 

[SS MAYFLOAT]

Re: Recharging A Fridge With 134a

Yep, you got a leak or a bit of moisture in the system. I would almost say it is a leak on the suction/low side of the unit. (the line with the frost on it) A company called Cliplite makes a product that can be added to stop real small leaks. I only use it when I've searched for leaks without finding them. There are sniffers, dyes, and soap like stuff to find the leaks. Leaks can be a nightmare to find sometimes. You should get in touch with the tech that charged it. With him charging it, he should have spent some time locating the leak. Freon does not get used up in the system.

The leak can be almost anywhere. If it was mine, I would mix up a solution of water and soap. About a 60/40 ratio. Apply it to everywhere that freon travels. I would start with your cold plate first. A pin hole in the aluminum tubing of the cold plate is a big possibility. If nothing is found there, then I would start checking all fittings and soldered connections. Also look for where the freon lines could have chaffed together wearing a hole in the lines.

When using the soap solution, make sure you shut the unit off. This will allow the pressures to equalize and helps finding the leak on the low side with a higher pressure. The pressure will only be higher on the low side when the unit is off. Good luck and be sure to let that tech know that there has to be a leak in the system.

If it turns out that it is moisture, a new filter/drier will need to be installed and the unit purged of the freon. Then a good evacuation of the system will need to be done. This removes air an moisture contaminates. Moisture in the system can close off or restrict the liquid freon going into the cold plate. This is a problem with the r134a freon. It acts like an attractant for moisture.

A way to tell is if you shut the unit off for about a half hour. Then turn it on. Then if the frost line returns like it did when he first serviced the unit, I would almost be certain that there is moisture in the system. If the frost does not return like it did after servicing, then it is a leak.