Samsung RF28K9380SR - 4 door - Pump Down & refill

[LtLaForge]

Short story - got this fridge for free about 18mo ago. Was told it failed not long after Samsung Cert Tech replaced the ice machine. Cust received a “coupon” for a new one. 

Charge was low. Vacuumed down, wouldn’t hold vacuum. Found damage at fridge cabinet evap coil inlet/cap tube conx. Repaired the connection using Lucas Milphaupt AL802. 

Vacuumed down, it held. Cut out & replaced dryer/filter. Vacuumed down for 1hr, held it overnight. Using 12oz harbor freight 134a and a postal scale added ~40gm thru low side motor service/process valve.

{Fridge also has a piercing valve(low side?) as well as a built in valve at Supco D111 dryer filter (high side) with the directional flow towards the Swing Valve.}
 

Plugged fridge back in, went thru self check and motor started. Continued a slow charge to -194gm. Motor picked up in speed. Coils started to cool. Left overnight. Came back to find compressor failed. 
 

Bought a salvaged compressor, swapped the compressor and replaced the dryer again. Vacuumed down, held, charged, started. If I recall correctly the low side was 1-2psi, high side 125psi.

Ran decent til last week. 

Freezer alarm went off, it was warm. Checked the charge, low>none. Found pinhole at my steel to copper solder job at the dryer.

{btw, I used a tinning flux to make the connection every time, but where I pinched the copper dryer to fit tight to the steel tube apparently was not the best and didn’t get enough solder.}
 

Replaced dryer (again), vacuumed down (again). It held overnight. Went to add charge and found frost forming at the dryers inlet (copper to steel connection). So I had a restriction somewhere right there. 
 

I figured too much solder or a pinch at the tube (inside the solder joint where I had pinched the dryer around the steel tube) was causing the restriction and pressure drop. 
 

Cut the dryer out , replaced and vacuumed down again. Started charging, low side goes into vacuum near end of charge. High side STAYED in vacuum & not building.

So sounds like I have a restriction between the compressor and the dryer as the high side port is part of the dryer, AFTER the copper/steel connection that started ALL this.
 

Right? 
Any other thoughts?
 

I have a Samsung service manual for the fridge but it does but have a pump down and fill procedures nor the optimal pressures.

To make things worse is this fridge has a “fancy” (variable speed) inverter compressor,  a 1->3 swing valve for the separately controlled cabinets and ice-maker, which is all new to me. 

I can’t seem to find a YouTube or anything that gets in-depth on the newer compressors. 
 

actually I found a video of a tech saying I needed to use an ammeter on the motor and base my charge off of the motors draw, but the comments ppl left were calling BS. So many different opinions.

Anyone have a proper procedure? Pressures, amp draw? Do I need to put the fridge into forced mode?

Lastly the process tube routing doesn’t make sense. The high side of the compressor goes to the condenser, out of that and into the back of the fridge on the right side, comes back out on the left into the dryer, out to the swing valve then from there to the three separate cap tubes just to go back into the fridge. So I really don’t know if there’s something else behind the panel that may be causing a problem, it is one piece from the compressor area all the way up the back of the fridge, hope I do t need back there.   Engineers.

I swear this thing only took a crap cause my wife was trying to get rid of our old side by side. Thankfully we had it for backup. Just give me a old single coil system plz!

I mainly work on auto systems & mby the occasional central air, but I have yet to pick up a bottle of nitrogen to purge and pressure test. Well that and a real scale, it’s a pain using that postal scale and a 12oz bottle. 
 

Thank in advance for everyone’s help. 

 

 

 

[Terry Carmen]

I don't have anything useful beyond that it needs to be sparkly clean inside the evaporators and condenser and yoder loop, and all the joints need to be perfect, and it needs a new, correct compressor and a new filter/drier.

Also, all the valves need to be removed and the holes brazed over, and it needs to be pumped down and hold a vacuum for at least several hours or even better a day.

Then you need to add the exact charge listed on the nameplate, seal it up and it should be fine.

Unlike auto, domestic refrigeration has pretty much no tolerance for any sort of contamination or leaks. If it's not perfect, you'll be back.

 

Edited September 6, 2022 by Terry Carmen

[LtLaForge]

5 hours ago, Terry Carmen said:

I don't have anything useful beyond that it needs to be sparkly clean inside the evaporators and condenser and yoder loop, and all the joints need to be perfect, and it needs a new, correct compressor and a new filter/drier.

Also, all the valves need to be removed and the holes brazed over, and it needs to be pumped down and hold a vacuum for at least several hours or even better a day.

Then you need to add the exact charge listed on the nameplate, seal it up and it should be fine.

Unlike auto, domestic refrigeration has pretty much no tolerance for any sort of contamination or leaks. If it's not perfect, you'll be back.

 

Thanks for the help. That “yoder loop” info was a help too. Nice to learn something new.

While researching the loop, I came across a vid for cleaning the coils and cap tubes. They recommend using the vacuum pump to pull some “thinners” about halfway into one side of the coil, then he purged it with 404. Then repeated the process on the other half (ran it backwards, in the out as it were), of course it would not be run thru the compressor.

So that being said, are paint “thinners” ok? If not what should I use?

Also do I need to use refrigerant for the purge or can I use Clean Dry Air?
 

Regarding the compressor, it is the correct compressor, though it was a salvaged by a appliance repair company. They have a storefront on eBay with good reviews, I thought it to be a safe buy.

The compressor does start and modulate it’s power. Do you really recommend replacement again? 

The filter dryer has been replaced every time the system has been opened/worked on or a leak found.

I was considering removing the piercing valve. What brazing rod do you recommend?

Regarding the other valves, the OE filter dryer has a valve built in, though it is positioned more like a sediment leg on a Gas line, unlike the aftermarket Sepco I’m using which is positioned parallel to the other line.

The compressors process line is the only low side access once the piercing valve has been removed. I am hesitant to remove it as it has been valuable in servicing the unit. The stem is/was new, with a good stem is it a necessity to remove it? I thought not having one was just mainly a deterrent to customers from messing with it.
 

Referring to you recommendation of holding the vacuum for a day, do you mean to leave the pump on or just see if it will hold a static vacuum?

Just to confirm everything is working do you have any idea what normal pressures I should be reading once it’s all said and done?

Lastly you have any recommendations on cycling the swing valve to the different coils?  I’m mainly asking As I do not want to have to cut the three different cap tubes from the valve in order to clean and purge them.

 

Thanks again

[Vance R]

41 minutes ago, LtLaForge said:

So that being said, are paint “thinners” ok? If not what should I use?

Also do I need to use refrigerant for the purge or can I use Clean Dry Air?

If your going that route use rx-11 and dry nitrogen to purge.

 

41 minutes ago, LtLaForge said:

What brazing rod do you recommend?

For copper to copper sil fos,  steel to copper at least 45% silver solder with Harris stay-silv black flux.  DO NOT overheat samsung steel - no red glow of the metal.

41 minutes ago, LtLaForge said:

Supco

These are fine, prefer the ones with dye.

 

41 minutes ago, LtLaForge said:

The compressors process line

I usually remove the pinched off tubing by unsweating the solder in a access valve stub.

 

41 minutes ago, LtLaForge said:

Referring to you recommendation of holding the vacuum for a day, do you mean to leave the pump on or just see if it will hold a static vacuum?

Wouldn't do it this way by using vacuum, use nitrogen and charge the system to the lowside design pressure. Lowside design pressure is on the model number tag. Leave pressurized for at least 15-20 minutes but, if you have time a day or two is good.

41 minutes ago, LtLaForge said:

Lastly you have any recommendations on cycling the swing valve to the different coils?  

 Just use the Forced mode to step through the evaps to check frost patterns

 

41 minutes ago, LtLaForge said:

Just to confirm everything is working do you have any idea what normal pressures I should be reading once it’s all said and done?

Use the forced mode to drive the compressor to full speed. My guess would be lowside 0 psi and highside would vapor pressure that is 20 degrees over ambient

Edited September 6, 2022 by Vance R
added over heating steel comment

[Terry Carmen]

Vance covered it all.

I recommended a day for holding vacuum because you seemed to have a leak somewhere, and it would be good to find it before finishing the job.

I would never trust a used or salvaged compressor for a customer machine. It might be okay but it's not worth my time to save a few bucks or a call back.

 

[LtLaForge]

bump   finally have some money and time to start tackling this again.

so have the Rx-11 kit on the way. 

regarding the flush, as the unit has a step/swing valve to switch between the individual evaps/compartments, would I need to disconnect this? Or can i use the front panel to switch between the evaps? 

If i need to disconnect it any tips/directions on the reconnection. i.e. flaring, ect.  

Lastly, looking at a few new compressors on ebay. one says it the box was opened for “initial inspection” and resealed. it has what appears to be plastic caps on the lines. is that normal from the factory or should the be pinched and brazed? 

also do the come typically with oil or do I need to add some with the refrigerant?

TIA

[Vance R]

5 hours ago, LtLaForge said:

it has what appears to be plastic caps on the lines. is that normal from the factory or should the be pinched and brazed? 

perfectly normal- when you remove the caps the compressor is pressurized with nitrogen. No pop or hiss - don't install it.

 

5 hours ago, LtLaForge said:

also do the come typically with oil or do I need to add some with the refrigerant?

compressor comes pre-charged with oil.

[LtLaForge]

On 12/8/2022 at 9:03 AM, LtLaForge said:

 

regarding the flush, as the unit has a step/swing valve to switch between the individual evaps/compartments, would I need to disconnect this? Or can i use the front panel to switch between the evaps? 

If i need to disconnect it any tips/directions on the reconnection. i.e. flaring, ect.  

TIA

bump— thanks for everyones help this far. Going to try to tackle this monster this evening and just need a bit more help. anyone able to answer my questions above?  

 

TIA

[Vance R]

On 9/6/2022 at 4:20 PM, Vance R said:

Just use the Forced mode to step through the evaps to check frost patterns

Use this answer.

[LtLaForge]

57 minutes ago, Vance R said:

Use this answer.

so just for clarity i am trying to flush each evap coil and the step valve is between the compressor and coil. 

Checking for frost patterns would be fine if the refrigerant returns to the compressor but there is a blockage and idk what coil it is in. 

so do you recommend putting it into forced mode for each compartment and performing the flush and purge then changing the compartment and repeating? 

[Vance R]

If going to flush the compressor and drier have to removed. To flush the evaporators the flush will into the input of the step valve then come out of the suction line. The step valve controls which evaporator will get the flushing agent. The output side of all the evaporators are plumbed into the suction line. The condenser and yoder loop should be flushed in reverse direction of refrigerant flow. When done flushing you’ll need to purge with nitrogen.