Glacier Bay Fridge/Freezer Help

[BigAl.NZ]

Originally Posted by BigAl.NZ

Yes! This one has the 1/2HP 650 RPM direct coupled motor. Looking to put oil in. Presume SAE10 as I can't find in manual.

Bycrick....can you pls check PM.

[BigAl.NZ]

After a few weeks cruising we have discovered (thanks to Ruuvi tags ( wireless temp sensors)) that the Carel display reads -20 - but the true box temp is only -5.

There are two thermocouples - one floating in air and the other is glued to the plate - we suspect the Carel is taking its readings from the plate - which is no good.

We tried to change the temp to -30 (to achieve a more realistic box temp of say -15) but after the carel reads -23. After -23 the transmission on the pump starts to slip.

So in summary it sounds like the compressor is not working at factory efficency - the cooling agent on the sight glass seems full, but not sure what else to do other than try to replace the cooling agent? (Maybe R12?)

Thoughts?

[Bycrick]

The Carel can be equipped with two sensors. One is to measure the temperature of the plate. The second can measure whatever you want, because it is for information only. The cold plate freezes at a temperature determined solely by the chemical mixture. So, GB wanted the turn-on temperature to be 4 degrees below the freezing point of the plate and the turn-off temperature to be 4 degrees above the freezing point of the plate. Nothing that you can adjust changes that. I don’t know what the freezer plate temp is, but the fridge plate was, I think, 28*. Thus the on-temp was 24* and the off-temp was 32*.

You can play with the set-points, but nothing will directly change the temperature of the box. What you’re supposed to do is adjust the plate set points up of down together, until the upper and lower temperature tails are similar, and then adjust both up and down trying to get the maximum time between run-cycles. The on-time has almost nothing to do with the box temperature; it’s controlled almost completely by the time it takes to freeze the plate.

[BigAl.NZ]

Thanks Bycrick - that all makes sense.

Our issue is really why the box temp is so high (-4C).

It could be the insulation is calling apart, the seals, compressor efficiency or all of the above.

I presume out of the factory it was meant to achieve better than -4C?

[BigAl.NZ]

PS: the fridge appears to work well. Holding about 3C and switching on breifly every few hours.

[Bycrick]

If it’s on "briefly" every few hours, it’s not set right. What they told me is that, in normal operation, the plate is supposed to thaw completely until the plate temperature is about 4* above the freezing point. Then the compressor turns on and cools the plate until the plate temp is about 4* below the plate freezing temperature. On my (from memory) 12“x20”x4” plate that takes an absolute physical minimum run time of about 45 minutes.

[BigAl.NZ]

Originally Posted by Bycrick

If it’s on "briefly" every few hours, it’s not set right. What they told me is that, in normal operation, the plate is supposed to thaw completely until the plate temperature is about 4* above the freezing point. Then the compressor turns on and cools the plate until the plate temp is about 4* below the plate freezing temperature. On my (from memory) 12“x20”x4” plate that takes an absolute physical minimum run time of about 45 minutes.

Fridge on for about 5-10 minutes every 2-3 hours.
Freezer more like 45 min every 8 hours.

I think in summary the question becomes if the plate is freezing (and I thin it is) why is the cooling effect not transferring to the box air temp.

[Bycrick]

I don’t have a freezer, but your freezer sounds like it is running better than the fridge part. When I first installed mine, it ran like yours is running. After a lot of emails back and forth, I ended up spending several months adjusting the parameters.

Get a bunch of graph paper, or figure out how to graph in a spreadsheet. Set the X-axis to time and the Y-axis to temperature. Make sure you’re measuring the PLATE temperature. When it turns on measure the temperature every 2 minutes until it shuts off. Graph the results.

What you SHOULD see is the first few (5-10) minutes will have a relatively quick drop, after the temp has dropped about 4*, it will stop dropping and run for 45-50 minutes with only about 1/2* change. You’ll get bored and think something is wrong. Then suddenly, you’ll have a very steep drop in the curve over maybe 2-3 minutes. Then it shuts off.

When i finally get things set right, mine would run about 50 minutes every 24-26 hours. It took me several months.

If I was doing it again, I’d try to find a way to record the time/temperature curve automatically. I wasted a lot of time doing it on paper.

[Bycrick]

Also, the temperature sensor is just a variable resistor. The Carel has an offset value that you can enter to "calibrate" the temperature. If you expect to display anything close to the "correct" temperature, you’ll need to calibrate it. One probe should be on the freezer plate, the other on the fridge plate. Id think box temperature would require some additional measurement sensor. But the actual temperature display doesn’t make any difference. What you want is the 8* differential between on and off setpoints. You adjust the two setpoints until the curve has the tails at both ends.

[Bycrick]

Re: post 34. The compressor efficiency will only influence how long it takes to freeze the plate. The system cares not at all what the box temperature is. It’s supposed to freeze the plate to a fixed temperature and then stop. How long it takes to melt the plate is a matter of how good is the box insulation.

[BigAl.NZ]

Hi Bycrick and others
We are back in home port now and I looked at the freezer again the other day. I actually have a Ruuvi tag in the freezer (on the wall opposite plate) so I can see (and its logged) something close to air temp in the box. Currently its alternating between 0 and 1.5 deg C.

Obviously I have my settings completely wrong. (I have just reread your post above.

Do you have any idea if the fluid levels in these two photos are Ok and what they are?

[Bowdrie]

Originally Posted by BigAl.NZ

Hi Bycrick and others
Do you have any idea if the fluid levels in these two photos are Ok and what they are?

I'm one of the "others".
Jeepers, that 2nd pic looks like an old open-drive Blissfield compressor.
Anyway, the first pic is the sight glass for the refrigerant, it's hard to tell whether it's completely empty or completely full.
That it shows a green dot is good, (no moisture).
If it's on the "off" cycle it will show empty, when the unit is running and nearing the shut-down point, (the TXV is throttled down,) the glass should show ~3/4ths full or a little more.
The 2nd pic is the sight glass for the oil in the compressor, when stopped the oil should be clean and show at ~1/2 the glass or so.

[BigAl.NZ]

Originally Posted by Bowdrie

I'm one of the "others".
Jeepers, that 2nd pic looks like an old open-drive Blissfield compressor.
Anyway, the first pic is the sight glass for the refrigerant, it's hard to tell whether it's completely empty or completely full.
That it shows a green dot is good, (no moisture).
If it's on the "off" cycle it will show empty, when the unit is running and nearing the shut-down point, (the TXV is throttled down,) the glass should show ~3/4ths full or a little more.
The 2nd pic is the sight glass for the oil in the compressor, when stopped the oil should be clean and show at ~1/2 the glass or so.

Thanks Bowdrie. Both photos were taken with pump running, so it looks like they are OK.

[BigAl.NZ]

Yikes - she starts making a horrible noise all of a sudden:

https://geekhelp-my.sharepoint.com/:...ncz3w?e=jsjQoq