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Post by ckfan on Jun 8, 2016 14:22:05 GMT
I'm honestly wondering at this point if it wouldn't make more sense to just try some contact cleaner on the old thermostat contacts. That is, if I can't make this new one work. The contacts just look dirty, they don't look pitted. I think that otherwise the thermostat looks to be ok.
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Post by Travis on Jun 9, 2016 1:31:58 GMT
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Post by ckfan on Jun 13, 2016 17:01:38 GMT
Well, I cleaned up the original thermostat contacts last night with contact cleaner and gave it a go. No luck. It is still somehow causing the overload on the compressor to trip out once the unit gets cold enough to shut off. I haven't tried the contact cleaning tool that Travis suggested yet but I really don't know if that would make a difference. I'm going to have to watch it tonight closely and see what is going on. I think it may be trying to kick on too quick after the long pull down. Or it could be just not making proper contact part of the time. I'm not sure. Every time I try it when it is warm it seems to work fine and bring the temp down though.
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Post by ckfan on Jun 15, 2016 0:23:46 GMT
Interesting update on the Norge. I decided to hook up the new thermostat without the knob and then hooked the capillary tube to the top of the evaporator plate in the back. I ran it overnight and it was way too cold when I woke up. 26! I then turned the knob to the warmest position and went to work. When I came back it was at 29. Hmm...
I decided to move the tube in between the back of the plate and one of the coils. This seems to have helped the temperature which has already stabilized around 36. This is at 1/4 knob position.
I decided to hook my power meter up and watch it cycle. I'm glad I did. It draws about 20 watts at rest when off. It then spiked up to 290! when it started. It fell off to 230 and then shut off after 13 minutes.
Here is where it gets weird. About a minute after it shut off it started drawing about 2300 watts and was obviously stalled. The overload quickly cut off and the watts dropped back to 20. Then I waited and waited. I expected the overload to kick back on but it didn't. Instead after 15 minutes the fridge just kicked back on and acted normal.
I thought this was very odd. I don't know a lot about how the supco relays work but I wonder if it is trying to kick on the start winding because of the heater draw across the thermostat leads.
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Post by timeswelding on Jun 15, 2016 9:50:28 GMT
Have you got it wired in such a way that the relay is seeing the load from the heater?
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Post by ckfan on Jun 15, 2016 13:23:29 GMT
I think that the relay might be seeing the load from the heaters but I am not positive. I will need to take a look at the wiring diagram tonight to confirm this. It is wired up really odd because there are about 5 wires that are split between the two leads from the thermostat. I really don't know what else would be causing the compressor to try and start but stall out when the thermostat itself should be off (only a minute after the on cycle ended). I wouldn't think that the thermostat would kick on within a minute and then the overload would take 15 minutes to re set. That just doesn't make sense to me.
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Post by coldspaces on Jun 16, 2016 2:23:51 GMT
Sounds like the thermostat did not stay off very long and tried to restart it before the pressures balanced out. From what I read the RO-81 will stay off about 5 minutes if the overload trips.
What heaters does this have, crankcase or defrost?
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Post by ckfan on Jun 16, 2016 2:38:47 GMT
I had a conversation with Travis and he convinced me that the thermostat must be kicking on too soon after it cycles off. I tested this just now and it is true. The compressor kicked on 2 minutes after it kicked off. I unplugged the cord and then hooked my multimeter leads up to it. It looked like the thermostat was on according to the ohm reading.
I decided to move the capillary tube to the side of the evaporator plate. Hopefully this will fix the short cycling problem.
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Post by coldspaces on Jun 16, 2016 2:50:14 GMT
That control should be a constant cut in of 39F. Were ever you hook the end it should have to get to 39F before it comes on. You do need 6" of more of the end touching the evap. Did they sell you a GC-402 or is that just what the box said?
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Post by ckfan on Jun 16, 2016 13:36:23 GMT
Gill, I'm actually not sure if the thermostat is a GC402 or not. I didn't check. I tried the new position last night and it didn't make much of a difference. The thermostat still tried to short cycle the machine. I'm either going to have to get another thermostat or think of a different way to mount the current capillary tube. I currently have about 4-6 inches of the tube on the evaporator. I tied it down with little binder clips running the whole length of the tube. I know, don't laugh. It is what I have to work with at the moment. I clamped the tube to the front of the plate with the clips going over the tube and plate. I'm not sure if this is just a poor position or if there is something else going on. I would think though that the plate would probably reach 39 pretty quick since the frost melts almost immediately after the machine shuts off.
To answer your previous question about the heaters. There is a mullion heater that is always on, it is 20 watts. There is also a "defrost heater" that is on when the machine is running and it is 6 watts and is strapped to the plate near the middle I think.
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Post by coldspaces on Jun 16, 2016 21:05:12 GMT
There should be numbers on the control housing.
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Post by ckfan on Jun 17, 2016 13:38:04 GMT
I'm going to have to look at the control housing to see if the numbers match. Last night I made provisions to use the original clamp for the sensing tube. I carefully drilled two holes in the evaporator plate (I could feel where the evaporator tubes were running) and then I mounted the sensing tube to the plate and made sure it was nice and tight. Well, I don't know if this would have fixed the short cycling problem because now the fridge won't shut off. It got down to 28 degrees in the door section before I tried to shut it off. It wouldn't unless I actually turned the knob to off. I think all of these issue center around the fact that I don't have enough capillary tube to properly mount it. Originally, there was enough spare tube to make a loop around the clamp instead of just one pass like I have it hooked up now. I can't get but maybe 3-4 inches to get into the clamp. Because of this I think that the thermostat didn't have enough sensing area to know to turn the unit off. If only the tube was just a bit longer! I'm really thinking about just putting in a "universal cold control" and being done with it. Not really sure what else I could do from here except for ordering a "more correct" thermostat.
Oh well, it is all a learning process.
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Post by ckfan on Jul 10, 2016 17:02:00 GMT
OK, quick update on the norge. This thermostat situation has been kicking my butt! I am so close to getting it to work now. I bought a "universal control" because I was getting frustrated with figuring out mounting options for the capillary tube. I got a supco unit and it works...kind of. The temperature was way too low at first. Around 27 degrees on the "1" setting. Now I uncoiled a tiny bit of the tube and put it behind and in contact with the evaporator plate. Now, miraculously the temperature is rock solid at 35 degrees. Great! Except for one thing...if you open the door after the unit cycles off it will short cycle. Ugh! The dreaded short cycle! If you don't open the door it will cycle pretty good. 8 minutes on and 13 minutes off.
I'm getting frustrated but am not giving up. I'm thinking that if I put something with thermal mass around the capillary tube that is coiled up it might just keep it from short cycling. Unless someone has another suggestion that is all I know to try at this point. I really want to like this fridge but I am getting a little aggravated to tell the truth. This is about the 15th try that I've done with the thermostat. Oh well, it's a learning experience.
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Post by icebox on Jul 15, 2016 20:55:47 GMT
I've seen this 'short cycling' problem before (on a new freezer), in the end I put a thin piece of perspex between the capillary and the evap. I've also seen the same problem on a computer room HVAC (small room and a lot of heat load), the solution was to put the electronic probe in a lump of expanded polystyrene - again worked a treat. So your thermal mass sounds a good solution, insulating the whole capillary should have the same effect. I have a freezer with just that set-up - from new, the whole capillary is surrounded by thick plastic pipe (about 1/3 inch outside diameter) I can only assume it's there to slow the cycling down. Don't give up, as you say a learning experience, and it's all good information for us fridge geeks. :-) Good luck!
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Post by ckfan on Jul 18, 2016 13:49:57 GMT
I've seen this 'short cycling' problem before (on a new freezer), in the end I put a thin piece of perspex between the capillary and the evap. I've also seen the same problem on a computer room HVAC (small room and a lot of heat load), the solution was to put the electronic probe in a lump of expanded polystyrene - again worked a treat. So your thermal mass sounds a good solution, insulating the whole capillary should have the same effect. I have a freezer with just that set-up - from new, the whole capillary is surrounded by thick plastic pipe (about 1/3 inch outside diameter) I can only assume it's there to slow the cycling down. Don't give up, as you say a learning experience, and it's all good information for us fridge geeks. :-) Good luck! Icebox, I think you are onto something. By insulating the probe from the air inside the cabinet it should keep it from short cycling. I was talking about the issue with my roommate (who wants the fridge out of the way in the kitchen) and he suggested something very interesting. He suggested to put the thermostat capillary tube in a liquid. I thought this was a good idea! So I took a baby food jar and coiled up the tube (on my thumb!) and stuck it in the jar. I then filled the jar with mineral oil and fired the fridge up. It looks promising. The fridge will not short cycle now which makes sense. The problem is that the fridge will get too cold before shutting off. So I think I have the opposite problem of what I had before. Now the thermostat capillary is reacting too slow to the cabinet temperature. It cycles off around 22 degrees and on at 38 degrees. I'm thinking that if I use a different liquid in the jar it may help. I'm just trying to think of what that may be. Water? Alcohol? Not really sure. I think I am going to experiment and figure out which liquid gives the best "thermal mass" to have it cycle right. |
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