Fridge too cold

Yoshimura · 01-30-2019, 08:35 PM

My new RV has a Norcold DC558 fridge and even at the lowest setting (i.e. 1), everything almost freeze. Also, I have the impression that the compressor never stop. Should I hear the compressor cycle? This is my first experience with a RV and we are currently traveling so any help will be appreciated!

https://www.thetford.com/product/dc558/

GeorgeRa · 01-30-2019, 09:17 PM

The compressor should cycle, I assume you have a capillary thermostat, see if the capillary tube, small copper tube, is intact. When you turn the thermostat know does it click (or use ohmmeter) at a point when the thermostat turns on the compressor. I would suggest to have Norcold folks fix it but later change to a 21st Century electronic thermostat.

rowiebowie · 01-30-2019, 09:46 PM

Thermostat would be the first suspect. However, they can run a lot even in cool weather conditions.

My Novacool 3.1cf (Danfoss compressor) works well and is very energy efficient. But the compressor runs practically all the time it seems. I mean it runs so much we notice the rare times it cycles off. The fridge is located next to the wet bath so it is quiet there and easier to notice the cycling. Getting up regularly at night is a fact of life for me now and even in cool temperatures (40-50 degrees) I hear it running the compressor surprising amount of time.

We've had a rare instance or two when fridge temperatures varied a little from desired parameters. Occassionally too warm to mid 40's or too cold and slightly freezing (only froze lettuce, never liquids), but we've rarely had to adjust the thermostat during a trip.

Good luck.
.

booster · 01-30-2019, 10:05 PM

Most of us would certainly not see the compressor frig run a lot of the time. Ours in cooler weather hardly runs at all, and at 100* in the sun right on it, it still cycled. If it is running all the time there is likely something wrong, but if it runs all the time and gets too cold, then I would agree it is likely the thermostat, and they have had issues with them.

If it has to run almost all the time to stay cool, you either have a bad frig or more likely, bad ventilation. Compressor frigs need to have good ventilation and that can be hard to get in a class b without extra fans.

Yoshimura · 02-02-2019, 12:51 AM

I noticed that when I turn the thermostat knob (Off - 1 - 2 ... 5), I can ear it click at 4 when turning it clockwise and at 3 when turning it the other direction. I'm correct to conclude that the thermostat works correctly? This lead me to conclude that the thermostat is working correctly, no? So the problem would be the control module. However, the compressor stop when I turn the knob to the off position.

booster · 02-02-2019, 01:09 AM

Quote:

Originally Posted by Yoshimura

I noticed that when I turn the thermostat knob (Off - 1 - 2 ... 5), I can ear it click at 4 when turning it clockwise and at 3 when turning it the other direction. I'm correct to conclude that the thermostat works correctly? This lead me to conclude that the thermostat is working correctly, no? So the problem would be the control module. However, the compressor stop when I turn the knob to the off position.

When you turn the knob you are turning it on and off and you could run it manually that way. If the tube is kinked so shut off or mostly blocked, the thermostat won't get a signal of pressure from the cold bulb to move between on and off, even though the knob will still work. Same can be true if the gas has leaked out of the bulb and tube.

I would turn it to one position where the compressor is just turned on and let it run a while until cool. Then turn it down until it just turns off. Open the door for a while and see if it comes back on or not.

Yoshimura · 02-02-2019, 01:32 AM

But what are those clicks I heard? When it clicks at 4, it detects that I want a colder temp than current temp, no? And when it clicks at 3, it detects that I want a warmer temp than current temp, no? Thus the thermostat detect that the current temp is either too low or too high, no?

It just seems that the module is ignoring the signal.

booster · 02-02-2019, 01:40 AM

Quote:

Originally Posted by Yoshimura

But what are those clicks I heard? When it clicks at 4, it detects that I want a colder temp than current temp, no? And when it clicks at 3, it detects that I want a warmer temp than current temp, no? Thus the thermostat detect that the current temp is either too low or too high, no?

It just seems that the module is ignoring the signal.

I am not familiar with what thermostat they use but normally you should be able to find 3 places that it clicks. One will be at one end or the other of the travel, probably at number 1 and that is the off position. Once you click away from that, should turn for a while and then click and that would be the on click for turning on compressor at the temp you are at. Turning it further will give no more clicks, but will make the frig colder before the compressor turns off. Once the compressor is on, and you have let the frig get colder, you should be able to turn the knob in the opposite direction until it clicks and that point should shut the compressor off. If it is not turning the compressor on and off, you could have a bad control board or the power to the thermostat is broken somewhere.

Yoshimura · 02-02-2019, 01:46 AM

I can heard the 3 clicks you described but unless to the Off position, the compressor runs. I left the door open for like 15 minutes and it now click at 3 and 2. Anyway, I don't have the tools or parts to fix it right now. Thanks for your help!

GeorgeRa · 02-02-2019, 01:56 AM

Capillary bulb (sensor) is usually located on the cold plate so it reads the cooling element temperature, if it is detached from the cold plate it will sense wrong temperature and continue run the compressor. Electronic thermostats tend measure inside fridge temperature.

Can you see the bulb location?

GeorgeRa · 02-02-2019, 02:02 AM

Is this the thermostat you have? https://www.ebay.com/itm/Norcold-634...t/113214328754

GeorgeRa · 02-02-2019, 02:18 AM

This thermostat has 3 blade connectors plus ground as seen on picture, likely the main power switch and the thermostat switch are in series. Turning on/off with the knob demonstrates that this circuit works, but the thermostat switch could be permanently closed - it could be closed if the bulb detects higher temperature than on cold plate (if the bulb is on the cold side) or the thermostat including its capillary is failing.

Electrical test of the thermostat would be valuable.

mumkin · 02-02-2019, 02:36 AM

There have been at least 50 posts on this problem on the Zion/Simplicity owners facebook page... including mine.

For most of us the fix is easy... someone on that page mention wiring. So when I took mine in to be fixed - assuming that it was the thermostat that needed replacing - I suggested that the tech look at the wiring into the thermostat. He switch the two wires... and it has worked fine ever since.

This has worked for most. A few people that it didn't fix ended up getting a new thermostat. So... open it up and switch the wires.

Chances are that this will fix it just as it has done with dozens of others. Norcold is apparently pretty slipshot.

Yoshimura · 02-03-2019, 01:15 AM

Quote:

Originally Posted by mumkin

For most of us the fix is easy... someone on that page mention wiring. So when I took mine in to be fixed - assuming that it was the thermostat that needed replacing - I suggested that the tech look at the wiring into the thermostat. He switch the two wires... and it has worked fine ever since..

A million thanks for this. It now fixed!!!!

The 2 wires were connected to pins 6 and 3 (instead of 6 and 4) and thus bypassing the temperature controlled switch!!!

rowiebowie · 02-03-2019, 02:40 AM

Geeesh! What ever happened to training and quality control.

Well, once again the great resources on this forum came to the rescue. Glad it was an easy fix.

.

mumkin · 02-03-2019, 05:00 PM

If only all fixes were so easy... LOL

Clearly their factory instructions were wrong, and when they tested it, they didn't cycle it. I have to admit that I did the same thing when I did my walk through on picking up the new rig. I turned it on and it turned on... and I thought it was fine. But then I kept reading posts about how the fridges were freezing everything. So I finally took the hint and went out to test it before heading to Arizona... and sure enough, I had the big freezer and no fridge too.

And two days later the underhood generator boiled my new AGM. (an issue that took time to develop... had been driving it for a couple months)

Can't really blame Roadtrek for these issues... these two came from the suppliers. That last one still isn't fixed and now I wait to see whether I will end up paying this repair on my own.

wabrower01 · 02-07-2019, 05:17 PM

Some units have had their wiring reversed, causing freezing.

RTVancampers · 02-08-2019, 12:34 AM

i had this same issue in a 2018 Roadtrek Simplicty SRT and it now works. Took it to a service repair center and the center stated they were told that the Tstat wires might be on incorrectly and to switch them. I dont know what that means, I'm no tech but whatever they did works.

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