Any refrigeration guys here?

[Redmt]

Our 4x6 walk-in freezer has never been set up by anyone that actually knows what they are doing. I have had it working pretty much ok for a few years but every now and then it gets a mind of it's own. I would gladly pay a professional to rub on it if I could find someone who would go out this far and work on it. I have a few questions if there's anyone here that would share their knowledge.

 

[warmer]

ask away, i'll do my best

 

[texwest44]

I have access to a refrigeration expert in my house. Decades of work on commercial and residential refrigeration and HVAC. He can't come to California but he can answer questions from the internet.

 

[Redmt]

It's 1/2 HP top of box 1 piece unit. The compressor was a little bit weak so put new head manifold head gasket valve stuff a couple years ago. New valve with appropriate plunger thing at the evaporator coil. All new drier, sight glass etc. I evacuated it over night. It held vacuum for a day so charged it with 410 until the charge stabilized. It had a very occasional bubble in the sight glass. 14-16* was the lowest it would go. It's been a little up and down a couple degrees for a couple years. 3-4 months ago it climbed to 20-22. The sight glass had many bubbles . I gave it a little bit of 410. The bubbles were back to very occasional and 12-14*. Today the temp climbed to 20-22 again. The sight glass was completely full and stayed full. I bled off a little 410 until it stabilized with occasional bubbles but the temperature doesn't want to drop.

 

[texwest44]

I am retired from the refrigeration business. Was in it for 30 years. From your brief description, I would say that you have a plugged screen in the suction service valve or the inlet to the expansion valve.
Hard to say for sure since you did not mention anything about pressures.
Hope this helps tp get you headed in the correct direction.

-texwest Sr.

 

[Redmt]

I am retired from the refrigeration business. Was in it for 30 years. From your brief description, I would say that you have a plugged screen in the suction service valve or the inlet to the expansion valve.
Hard to say for sure since you did not mention anything about pressures.
Hope this helps tp get you headed in the correct direction.

Ok,,,part of my problem is that I don't know what all the pieces are called. Where is the suction service valve? The expansion valve is the valve inside the box at the evaporator coil, right?

 

[texwest44]

Yes, the expansion valve is in the box above the evaporator coil. The suction valve is on the side of the compressor where you mount your gauges. The suction side will be cold, and the discharge side will be hot.

-texwest Sr.

 

[Redmt]

Expansion valve

 

[Redmt]

Suction valve?

 

[Redmt]

BTW it's 404a and I'm not sure how much I have left.
There's also this on the outside too. I'm guessing it's the actual thermostat?
Box temp is at 18*

 

[texwest44]

Yes, that is the expansion valve. Due to sweating, I would say yes to suction valve. There should not be that much ice on the outlet of expansion valve. Frost in that location generally indicates low refrigerant charge.

 

[texwest44]

The other photo is the low pressure cut out control(a safety switch).
Is there any frost or ice on the face of evaporator coil?

 

[Redmt]

Okay, seeing as how I'm not sure if I have enough 404a left to completely recharge it, should I just add a little Freon to it until the bubbles disappear?
There's no ice on the evaporator coil that I can see. I will get a mirror and check the fan side.
I have other freon types. Could it be changed over easily to something else?

 

[texwest44]

No, it cannot be easily changed over to something else. That would require changing the expansion valve. The expansion valve and the freon must match, the valve is designed for specific freon.

If the valve is designed for 404a, avoid putting any amount of 410 into the system. What 404a you have left you can add, but I don't think it will solve the problem permanently.

It seems to me that the freon levels are low, and if you're adding freon and it's still low, then that signals that there is a leak somewhere.

-texwest Sr.

 

[Redmt]

I miss spoke saying 410. I shouldn't work from memory. It's 404a.
It seems my temporary fix is going to bump the charge a bit then get some more 404a then pull it apart, look for plugged screens and clean and recharge it. I'll try and get by until the cooler weather gets here. If I screw something up then I won't have to be scrambling as much to get it right.

 

[texwest44]

Yes, when you eventually get to opening the compressor, make sure you've dumped all of the freon. Takes quite a bit of suction.

Do you have any refrigeration gauges? It would be good to know some pressures.

Also, can you check where the low pressure switch connects to the compressor? Does the capillary line run to the side of the compressor or the suction service valve? Hopefully it runs to the side of the compressor, because that would indicate there's no plug in the suction service valve.

And I should ask what temperature you're looking to maintain, and what is your thermostat set for?

texwest Sr.

 

[Redmt]

I have an automotive type vacuum pump. It draws down to around to -25 .
I do have some gauges.
Is the capillary line the little 1/8" line? I'd have to check to see where it connects.
I'd like to see around 10 or maybe a little less if possible.
I'm not sure about the thermostat. Is that the little square box in one of my pictures?
Another thing, I was trying to guess how much 404a I have. I have another full cylinder of Solstice N40 (R-448A) . It says it's a 404A replacement. Would that be a direct replacement? Out with the 404 and in with the 448? That seems like it would be a great way to go.

 

[texwest44]

The thermostat should be inside the freezer itself somewhere.

Not sure about the 448 - it might be ok as a complete replacement, but should not be mixed.

What kind of pressure do your gauges show? You should be measuring directly from the compressor. Suction should be around 20 pounds, and discharge should be around 250, I think. I'm used to freezers running closer to 10 below 0 rather than 10 above.

 

[Redmt]

I'll see what I can find about the 448 as a complete replacement.
There's no thermostat in the box.
I wish you were closer or I was better educated.
Edit. It says it's a replacement but it sounds like there's other things that need to be done also. I'll get some more 404

 

[texwest44]

Luckily all refrigeration systems work basically the same, though every manufacturer may have their specific designs.

I'm curious to where your thermostat is. How is the temperature controlled if there's no thermostat in there? Curiouser and curiouser, said the HVAC engineer.