CK model Keeps starting and stopping issue

Jul 11, 2019 21:43:50 GMT mygemt said:

Thank you for your information. If the box can be opened can the points be cleaned? I have special jeweler's files and all kinds of sandpaper grits. I had to do something like this on a washing machine timer years ago and it fixed it as the points were not clean any more. If anyone can give me some insight as far as removing the box or opening it safely I should would appreciate it and thank you turbo for your help! I'd hate to lose this 83 year old family fridge.

I know the feeling! It's important to respect that your family has owned it since new. I would definitely be very cautious with the repairs, because it is possible to damage the relay in a manner which could burn out the compressor motor.

The relay can be refurbished, that's for sure! But it's probably not a matter of dirt, it's a matter of all the actual contact surface (silver alloy button?) is completely gone; allowing the two brass contact supports to weld to each other. You can probably un-stick it but it will only work a few times.

I have salvaged contact points from automotive relays and soldered then in position to replace missing points before. It was on a Frigidaire relay but similar principle.

The most important thing is to use a power meter to measure what sort of power demand and current the motor has. This will keep you from burning out the motor even if the relay or wiring is bad. The motor should draw 3 amps or so when running. If the start circuit is stuck, it will take a lot more, possibly 8 or 10 amps. If it continues to run like that and the overload doesn't trip the compressor motor will be destroyed. The meter will allow you to verify your work and give you the opportunity to power it off and re-do the job if the current draw is too high. Most of use the "Kill-A-Watt" meter which is available online or from Harbor Freight Tools.

As far as removing the relay, it comes up out the top. Originally, there was enough cable slack to lift it up and determinate the wiring on the relay, while it was just above the top of the condenser. With old wiring, it will still come out that way, but the wiring will probably crumble up in the process. That's OK because it has to be fixed. The wiring will have to be replaced to fix this problem no matter how you look at it.

Please (please) read this thread. There is a lot of info and pictures. It may seem overwhelming but it's not. You just need to approach it knowing it is not an instant fix and that you will need to prepare to spend the time and allow the fridge to be out of service until it's done. monitortop.freeforums.net/thread/723/re-wired-ck

Sincerely,

David

Jul 16, 2019 17:43:34 GMT mygemt said:

There was something very odd that happened last Friday. The trouble with the smaller monitor top that we used for years seemed to almost correct itself! It was starting and stopping for days on end. Then it must have heard it was going to have to be repaired or replaced. Suddenly on Friday of last week it was not starting and stopping but did it more regularly. There had been a frost pattern exact way it has been for years....all the way down the left side, the bottom and about 60% on the right side. Little by little over the days it returned to the old pattern and stayed there. Maybe there was corrosion on the relay's points and somehow it righted itself? I don't know.
It really needs a paint job and a new seal so we removed it and we installed the other monitor top the CK2 C16. I purchased this unit about 30 years ago and never used it. It was packed away in my garage. After testing it for days and cleaning it, the new CK2 is in our kitchen. Now I have a fridge with a light in it, a sliding food shelf and a porcelain drawer on the bottom and a foot switch. Everything is all original and looks just tip top. I bought this from an estate sale from a lady that came to American and purchased it new along with a Singer Sewing machine. She kept both items in superb condition. It's bigger than the other unit but we got it to fit and we are happy. 
I definitely will not forget about the other as I really want to find out what was going on and fix it....then do the cosmetic work. I will be back looking for suggestions I'm sure.
Thanks guys....sure appreciate your help!

Glad you got your "new" MT in the house an in operation! As for the problem correcting its self, that is very indicative of a stuck start-relay contact. It finally freed its self. It's very bad for the motor to let it continuously start and stop on the overload breaker like that! The overload has another set of contacts similar to the start relay. If those were to stick, while the start relay is stuck, the results will be catastrophic.

To explain what would happen if the start-relay and the overload contacts both stuck at the same time, here is a video. This was an already-damaged motor from a compressor which was not repairable. This was really hard for me to do, standing there and not intervene at all, while it died.  But, it didn't die for nothing as we have learned a lot from it.

www.youtube.com/watch?v=fMK8WYmO9Vo

Jul 17, 2019 22:56:39 GMT mygemt said:

Thank you again Turbo. This is  very interesting. I think I have no choice but to check out the old relay and anticipate the rewire, etc.
It's great to see everyone so dedicated to keep these machines alive. There used to be someone in San Diego back in the 90s I believe that restored these completely, recharged them and made parts, but they are no longer around. He did everything and I mean everything from the flyer I received from him. He was a commercial refrigeration man.

Many thanks!

Yes, those old timers are sadly, becoming fewer and further in between as the years pass. Several of us here are of a younger generation who never saw these machines when they were new. I'm less than half as old as many of the Monitor Tops. My interest in refrigeration comes from my grandfather, who taught me the principles when I was a little kid. He taught me also a lot about electrical and mechanical in general.

He also foresaw the problems we have today in society; such as the lack of skilled tradesmen. Even way before the Internet was a thing; my grandfather said that "If your skills only include talking and writing as the final act where the rubber meets the road - you can be replaced with a phone or a fax machine." He really hit the nail on the head with that one.

The flip-side of that is; with all the available information and communication - even those of us (such as me) who are relatively new working on Monitor Tops can locate the necessary information to be successful. But again - that success depends on having the basic hands-on skills to execute the repairs afterfinding the information on how to proceed.