RV Danfoss Help

[lisney56]

Hi, first post so please be kind.
Waeco 190lt 2 door upright with a Danfoss BD50 compressor and R134a. Fridge is 5 years old.
2 years ago it lost its *****. Leak was found and repaired by fridge tech however, when started
was not right. Low side running in vacuum. Tech had to replace cap tube as it had a blockage.
Then all was great until a couple of weeks ago.

Fridge lost ***** again. Leak was located in the same area as before, where the steel evap
line (corroded) joins a copper line before entering accumulator. This time copper line extended so hopefully won't happen again. Same as last time, he purged with nitrogen, vacuumed system and charged the system. Same as last time, wouldn't come out of vacuum on suction side. He stated that the cap tube must be blocked again. So cap tube replaced again, vacuumed and charged.

Now for the problem. Still pulls a vacuum on low side. Critical charge is 150 grams. Tech put in 190 grams trying to see if it would come up to his recommended 5PSI.
Fridge not cooling, compressor running too hot, returning ***** not cold enough.
Also compressor amp draw is down from the normal 2.3AMPS it always ran at to only 1.8AMPS????

Tech man seems a bit stumped. The evap is enclosed inside cabinet but measured temp in freezer (through plastic lining) is -6* Celsius max. Evap runs down back of freezer and behind top 1/4 of fridge, so no internal fans etc. ( just trying to give you all the info I can).

When he repaired the leak this time, the accumulator was removed and he said it had 30mls of oil in it. He then said that, as no oil was replaced last time, he will add a bit extra this time to be sure it had enough. So he topped up the compressor with 65mls of POE oil???
Now he says that it might contain too much oil and it is clogging up the system???

I need some advice as I am starting to loose confidence in his ability to solve this problem.

Why spend so much time on a small upright. It is enclosed in a motor home and hard to replace with the same size without major remodeling. Also cost over $2300. This tech has been good as he has let me do the time consuming work like cutting out the back and removing the foam. Then rebuilding the unit after he has completed the repairs.

So any advise would be greatly appreciated. Thank you.

[lisney56]

hello, I just spoke to another fridgie who said he thinks the compressor valves might be leaking.
Any thoughts on that one?

[mikeref]

No mention of drier replacement. Capillary tubes on small fridges can easily block up with any contamination including particles from the drier. Also, too much oil in the system can lead to less efficiency and oil logging in the capillary tube.

[lisney56]

Thanks mikeref, drier has been replaced three times. once during first repair 2 years ago, and twice this time.
Once after the leak was repaired, and again after the cap tube replacement.

[mikeref]

Each time the fridge sprung a leak, there was a good chance of sucking in moisture. If the compressor oil has moisture in it, then just vacuum alone will not remove this. The small copper driers don't have much capacity to keep the refrigerant dry. Might have to remove the compressor and change the oil. Only way to be sure as there is no oil glass on the compressor.

[lisney56]

Thanks again. How much oil is likely to be up in the system? I have read that if a system has too much oil, it can be difficult to estimate how much oil to put back into the compressor. This system holds 150mls.

[mikeref]

Thanks again. How much oil is likely to be up in the system? I have read that if a system has too much oil, it can be difficult to estimate how much oil to put back into the compressor. This system holds 150mls.

What i would do would be to remove compressor and drain the oil by tipping it on its side. The oil will drain out of the larger of the 2 pipes. Oil should go into a clean measuring cup to determine quantity and condition of the oil. Looking for oil to be a light tea colour. If there is any moisture in the oil, it will show up as liquid drops under the oil after letting it stand for a few hours.
I'm not concerned about oil quantity in the rest of the fridge circuit at the moment, however your mechanic will know how to do the next step.
Weld in a 1/4 inch access valve to the suction line and remove capillary from the drier. Pressurise with dry nitrogen and catch whatever comes out of the capillary. Need about 150 ish psi pressure. Be patient as sometimes it takes more pressure to push oil out of such a small tube..Mike.

[lisney56]

Thanks for your wisdom mike, the repairer will be here tomorrow. The more insight I have the better.
Many thanks, Lindsay

[mark957]

Too expensive repair that will not give security, I think you might consider replacing the refrigerator.