CK Rewire and control tube repair....

Mar 3, 2019 14:54:57 GMT birkie said:

Mar 3, 2019 14:20:11 GMT turbokinetic said:

I noticed the cracked sensing tube for the bellows, which would prevent the unit from starting. I am hopeful this is the extent of the problem.

Fingers crossed that's it. I believe those used methyl chloride. Closest fit would probably be your good old friend R152a with a few minor tweaks, 'cause I just know you're going to try to repair it

The nameplate is not in good shape. I do believe this is a replacement CK cooling unit on an older DR cabinet. Hopefully someone can confirm.

If that's a CK-2-D16 (it looks like it from the outside), then it's a replacement. It's hard to tell from the photos, but it looks like a CA cabinet. So maybe I'd guess the original CA top failed in 1941, when it was replaced with a unit from the 1938 batch of CK replacement tops they made.  The final batch of CK tops was made a few months later, in 1942 (albeit with a blue porcelain evaporator of a different design than the classical CK evaporator)

What's that?  A low-side service port?

I believe on your flat top you'll see a similar port, albeit on the top of the compressor dome. They did that starting in 1938, as an alternative to the pinched-off float bypass tube. The manual strongly warns against tampering with it, but I've never investigated why. On my flat top, it looks like it could be a standard purge screw, but I've never tried to find out.

Hi Thanks Aaron. I need to get some better pictures of it to help with identification. It was late last night and I just dropped the trailer in the barn and took a few picts. Will get into it today.

Will be repairing the sensing tube, for sure. Thanks for the pointer about the methyl chloride. I'll try R152A in it. Thankfully it seems that there's quite a bit of adjustment to the control. Once there is any saturated gas in there, and it is "functional" I should be able to dial it in so that it is reasonably correct on the temperature.  Sort of like with John's DR control tube.

Hopefully this one won't need refrigerant system work. If it does, then that low side port would help with the evacuation process. That's always an area of concern on these since the low side might not get pulled down effectively otherwise. I have been running the compressor to help pump the remaining air / gas to the high side, so the vacuum pump can remove it. But, that is stressful on the compressor. Really not much other way though.

Mar 3, 2019 16:00:44 GMT ckfan said:

I’ve always wondered about that port too. I’ll have to look on my flat tops to see but there is for sure one on my 36 CK C16.

In looking at the port again today, it seems to have a plug screw, but no external threads on the port, to attach the service kit. Would probably require a special tool, or the port to be modified.

So; got some progress on this one today!

First, got it unloaded from the trailer. I like the more highly stylized control bezel on this one.

Looks like an older cabinet with a CK unit on it.

It's so Art-Deco!

Inside is clean, but the cabinet light wiring is incredibly bad.

Had a little clang and bang action there on the back. That will need some straightening, or it may cause an air leak into the cabinet.

It's pushed in about an inch.

I found a clue as to some of the problems.  The taped splice was intermittent. After cutting that off, I was able to get consistent resistance readings.

The wiring at the relay was also a horrendous travesty.

Even worse under the relay cover!

The relay was worn out without any contact points left. I replaced the parts of the relay with the contents of a Supco RO81. Looks the same, but now it's solid state.

On to the wiring. Insulation still clean and soft.

Wiring is ultra crispy.

Now it's gone.

And new wiring is in its place!

A test run.

Relay with new wiring in place.

The power cord and the cabinet light power feed.

Function testing the cabinet light circuit.

Canvas tape to replace the destroyed No-Oxide cloth that was originally here.

Set in place and connected! The whole system is 100% bonded and grounded. The top assembly is grounded. The cabinet shell, cabinet interior, and the door light switch are all bonded and grounded.

Made a short video today - it rained too much and I couldn't make a detailed video because of the noise.

Moved one step closer to having this fridge ready to "go home." The control is once again functional.

As explained previously, the sensing tube for the control had a nasty cut in it, which almost looked like a wire cutter nip. That sensing line is 3/16" copper tube. I drove to several places today and finally found the correct size copper tubing at an automotive parts store.

The tube was soldered in place of the original, then charged with R152A. It was then pinched off and soldered. This is just about the same process used on the original one.  I made a video with a lot more details than the pictures here show.

Old sensing tube cut off. The connector piece from the bellows is cleaned up and ready to solder. The wet paper towel is there to block heat from going all the way back to the bellows and possibly desoldering parts of it.

Charging. The vacuum pump and R152A can are connected to the blue and red ports on the gauge manifold. The yellow port (the center) goes to the new control tube.

Finished. The new tube is slightly longer. I gave it a little extra so that I could mess up a few pinch-and-solder ends and still have enough LOL!

Looks slightly different but the function should be the same.

Lots more details here:

Mar 5, 2019 3:47:27 GMT coldspaces said:

Great work as always, glad to see your main malfunction was the control and wiring. That tube got damaged while defrosting with a sharp object IMO. Good old wet paper towels make as good a heat sink as any.

Thanks!  Yeah, that is quite likely. I've never understood the desire to scrape or chip off ice from the evaporator. Just seems like a bad idea all-around; but so many of these fridges get damaged in this way. Remember the 1947 Frigidaire I got with the punctured evaporator? It still had the original plastic ice scraper, in its instruction package, with the fridge.  However, that didn't stop the previous owner from puncturing the coil with a knife or some other sharp object.  At least in that case, it was not an SO2 system.

I have a feeling that the bad cord splice confused the troubleshooting done previously by the local service technician. He apparently determined that the control wasn't working, but then could only get the unit to run for just a second or two, by bypassing the control. That was surely because of the bad splice.

Mar 5, 2019 12:32:06 GMT ckfan said:

Very impressive stuff! Great work as always.

Mar 5, 2019 12:54:29 GMT solarmike said:

Very nice.... I learn something every time you restore something.... Many thanks....

Thanks, and very happy you found it helpful. It seems there have been quite a few broken control tubes which were the cause of folks giving up on their MT's. That makes it more important to document the repair and hopefully encourage others to (at least) give it a try!