# SubZero 211RFD Temperature Variation



## BayouRunner (Feb 5, 2016)

Is the compressor cycling off? Or is it running al the time? I had a customer with the same setup about 5 years ago where I replaced the compressor but I used refrigerant 409. I can't speak for the hot shot as I haven't used it. We did another one a few months back as well.


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## DanS26 (Oct 25, 2012)

BayouRunner said:


> Is the compressor cycling off? Or is it running al the time? I had a customer with the same setup about 5 years ago where I replaced the compressor but I used refrigerant 409. I can't speak for the hot shot as I haven't used it. We did another one a few months back as well.


I believe the compressor is cycling properly. I monitor the the electrical use of the Subzero with a CT clamp on its dedicated circuit. It is a TED500 monitor. I know how the system absorbs power...ie when the compressor kicks on...when the system goes into defrost cycle...even when a door is opened. I know how long a cycle takes. 

It is an energy hog...sucks about 7 to 10 kWh or around a $1 per day. Yeah, I know. But if I replace it will cost over $10k, maybe more. I won't live long enough to see a positive return to replace. Some things are best to just repair.


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## hkstroud (Mar 17, 2011)

I had a SubZero for about 20 years. Yes, it was an energy hog but I liked it. Finally had to give it up because so much condensation got between the walls it lost all its insulation. When I pulled it out I actually pulled dry wall of the wall. It was frozen to the wall.
Finally replaced it a couple years ago. Replaced it with a GE Monogram. I'm still in the process of making the panels for the replacement. Actually have the panels made, just have to stain and finish them. Wife finally figured out that *****ing doesn't speed me up.


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## Druidia (Oct 9, 2011)

DanS26 said:


> Here's the problem.....I'm getting large temperature fluctuations in both the refer and freezer. The Refer will fluctuate from 27 deg to 45 deg. The freezer from -5 to 23 deg. Yes, I know not good. What is interesting is that when the unit warms up it actually uses less power so it appears that the compressor and the sealed system is operating OK. Is it possible that the Sure Shot stuff is not a good replacement for R12? I've installed a dryer on the line also.



What is your thermostat dial setting? 

I have a 13-YO built-in (Northland). With the thermostat set at 3 (range of 1-5), min and max freezer temps are -7.6 F and 17.6 F. 

I read that the recommended range is supposed to be -18 to -21 C (-0.4 to -5.8F), not sure if I remember that right. I could lower the max temp of my freezer by setting the thermostat dial to 4 or 5 but is it really necessary? 17.6 F is well below the freezing point. The air temp in the freezer is 17.6 F but frozen meat inner temp is lower (but not measured). I haven't timed how long it stays at 17.6 F during the defrost phase.


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## BayouRunner (Feb 5, 2016)

Just trying to figure out what's going on. My guesses would be as follows. Compressor runs gets hot, cycles out on overload the. When it cools down it's coming back on causing a wide temp variation. Could be as simple as a bad thermostat. One thermostat works for both units? Most of the ones I work on have separate compressors for frig and freezer or are entirely separate units


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## DanS26 (Oct 25, 2012)

Druidia said:


> What is your thermostat dial setting?
> 
> I have a 13-YO built-in (Northland). With the thermostat set at 3 (range of 1-5), min and max freezer temps are -7.6 F and 17.6 F.
> 
> I read that the recommended range is supposed to be -18 to -21 C (-0.4 to -5.8F), not sure if I remember that right. I could lower the max temp of my freezer by setting the thermostat dial to 4 or 5 but is it really necessary? 17.6 F is well below the freezing point. The air temp in the freezer is 17.6 F but frozen meat inner temp is lower (but not measured). I haven't timed how long it stays at 17.6 F during the defrost phase.


Thermostat is set at 5 out of 10. If I move it up to 6 then things start to freeze in the refer section.


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## DanS26 (Oct 25, 2012)

BayouRunner said:


> Just trying to figure out what's going on. My guesses would be as follows. Compressor runs gets hot, cycles out on overload the. When it cools down it's coming back on causing a wide temp variation. Could be as simple as a bad thermostat. One thermostat works for both units? Most of the ones I work on have separate compressors for frig and freezer or are entirely separate units


Bayou I think you are on to something.

I recharged the unit with HotShot 2 but I could not find exactly how much of that refrigerant to use since the SubZero calls for R12. The door panel specs call for 14 oz of R12. What is the right amount of HotShot 2 to replace the R12?

So if I undercharged the sealed system I might be seeing the compressor timing out on overload and that is also why the unit is consuming about 50% more energy than original specs. What do you think?


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## BayouRunner (Feb 5, 2016)

Keep in mind I'm not looking at it but I think it's low on refrigerant and the compressor is overheating and taking a while to come back on. Can't tell you the right amount sorry as I've not used it before. Make a call to the company maybe they could tell you. Suction line should feel cooler if it's been running for a while. If it's warm the I'd say undercharged. If it was overcharged the auction line would be freezing back to the compressor. If you could get a quick glance at the Evap coil it should be frozen all the way across the coil after it has been running for a while. If it's not you need more refrigerant. Problem is you can't always see the coil but on some of those old ones you can. Next time the compressor cycles off and your temperature is still warm check and see if you have power to the compressor. That will be the seas giveaway there. As compressor will be warm or hot but have power and not be running. It's kind of tricky when your using different refrigerants . I've not had enough of them to warrant a whole lot of research. But I understand that the unit is part of your cabinets so to speak so you've got to keep it going


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## BayouRunner (Feb 5, 2016)

Can't edit my my post but it's suppose to say dead giveaway not seas.


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## DanS26 (Oct 25, 2012)

As luck would have it....now I find the conversion Guidelines for Hot Shot 2. It says that the initial charge of Hot Shot 2 should be 80% of the original R-12 charge. Then goes on to say ....if additional Hot Shot 2 needs to be added, do so in 5% increments and DO NOT exceed 115% of the original charge of R-12.

But I should only do this by checking pressures, subcooling, and superheat temperatures. Sounds like an excuse for me to buy more testing equipment....hahaha.

Anyway, thanks for your help. I may need to bring in an expert with all the right equipment.


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## hardwareman (Oct 9, 2010)

sounds like a thermostat problem to me. Where are you taking these temps? You said you replaced the thermostat. Does the thermostat sensor connect to anything or is it just sensing air temp. Hot shot back in the day was a very good substitute refrigerant with no problems


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## hardwareman (Oct 9, 2010)

DanS26 said:


> As luck would have it....now I find the conversion Guidelines for Hot Shot 2. It says that the initial charge of Hot Shot 2 should be 80% of the original R-12 charge. Then goes on to say ....if additional Hot Shot 2 needs to be added, do so in 5% increments and DO NOT exceed 115% of the original charge of R-12.
> 
> But I should only do this by checking pressures, subcooling, and superheat temperatures. Sounds like an excuse for me to buy more testing equipment....hahaha.
> 
> Anyway, thanks for your help. I may need to bring in an expert with all the right equipment.


I have never worked on a sealed system that I couldn't get an approximate charge in by nothing more than the feel of the suction line. The suction line should be a little colder than room temp after the compressor has been running for a while. To cold and frosting, indicates over charge too warm indicates under charge. Just a thought to give you an approximate idea of the charge


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## DanS26 (Oct 25, 2012)

hardwareman said:


> sounds like a thermostat problem to me. Where are you taking these temps? You said you replaced the thermostat. Does the thermostat sensor connect to anything or is it just sensing air temp. Hot shot back in the day was a very good substitute refrigerant with no problems


You know hardwareman....before I go off screwing around with the sealed system, I'm going to replace the thermostat. As Sherlock Holmes would say check the obvious first before grasping at straws. Large temp swings would indicate a temp control problem....I'll start there.


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## hardwareman (Oct 9, 2010)

DanS26 said:


> You know hardwareman....before I go off screwing around with the sealed system, I'm going to replace the thermostat. As Sherlock Holmes would say check the obvious first before grasping at straws. Large temp swings would indicate a temp control problem....I'll start there.


I never suggested you screw with the sealed system, I simply pointed out that you can get a good idea of your charge by feeling the suction line


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## DanS26 (Oct 25, 2012)

hardwareman said:


> I never suggested you screw with the sealed system, I simply pointed out that you can get a good idea of your charge by feeling the suction line


I was trying to agree with you because you had a good suggestion.

Here is what I still don't understand. The compressor and sealed system must be fairly good since the unit will cool down to the proper temps. The unit does not go over 47 deg on the high end. So it seems to me that the thermostat is also working properly on the high and low end but maybe not in the middle temps. Although I did notice that you can adjust min and max pot on the back of the thermostat.

The compressor is stopping above the min temp called for by the thermostat. Only three reasons I can think for that.....one the defrost cycle kicks in or two, the thermal switch on the compressor opens so that a compressor cool down is accomplished or three, the thermostat stopped the call for cooling for some reason.

So my only conclusion is that the cooling capacity of the system is somewhat diminished because it takes too long to get to temp. A few things could cause that:

1. An undercharged system
2. A weakened compressor
3. Blocked condenser coils
4. Condenser fan not working properly or just dirty
5. Door gaskets not sealing properly
6. The insulation around the unit is compromised...wet, iced up or fallen down.
7. The thermostat is compromised by touching metal, icing up or just not operating correctly.

Any feedback is welcomed and thanks for your help.


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## BayouRunner (Feb 5, 2016)

Easy to tell if it's the thermostat. Just do like I suggested above. When compressor cycles off and it's still warm check for power to compressor. If it had power you most likely have a sealed system issue. If it doesn't have power then either it's your thermostat or defrost timer is sticking.


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## BayouRunner (Feb 5, 2016)

Also could be a defrost control stat that is bad. But verify if it has power to compressor first and we can guide you from there.


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## DanS26 (Oct 25, 2012)

BayouRunner said:


> Also could be a defrost control stat that is bad. But verify if it has power to compressor first and we can guide you from there.


I have replaced both the defrost timer and the defrost thermostat.....but that does not mean the new parts are working correctly. I believe I can tell if the defrost cycle is not operating properly by looking at the electrical use of the unit. There are three fans, a compressor and three lights that consume power beside the defrost heating element. They all use power at different levels and at different times but my CT clamp on the circuit should help me decipher what is going on and when. I'll have a closer look.


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## BayouRunner (Feb 5, 2016)

Well then if it's still the same problem I would not worry about the defrost timer or stat. It could be the thermostat but they have gas in them and when they leak the temp goes up. I don't think it would go down to zero then to 45. But you will have to test to figure it out. I wouldn't buy parts and change them. Another scenario is the unit is slightly low on refrigerant and the ice is building up around the top of the coil and not freezing at the bottom. Then it builds up ice around the defrost stat and when the defrost cycle kicks in the unit does not go out of the defrost cycle and the unit gets real warm until the timer starts back up. Some of those old sub zeros don't have a defrost heater so I can't say for sure what you have. They just blow the fan across the coil to thaw the unit.


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## DanS26 (Oct 25, 2012)

OK guys I think I know what is going on with this SubZero 35 year old senior refer/freezer.

The compressor will run for hours and slowly cool the freezer and refer. During that time if the defrost system kicks in then the refrigeration process will stop and the box both freezer and refer will warm up until the timer resets. Then the compressor will again try to cool to the low temp set point.

So not only is the defrost system adding heat to the system but any door activity will aggravate the warming process.

The sealed system has just enough refrigerant to keep this cycle going. So the compressor is running overtime just to keep up....sometimes it is not enough and the whole box heats up.

I have used a IR gun to determine the compressor temp...around 145 F so the compressor is not shutting down on high temp. It is just running inefficient because of low gas.

I'm going to add some more Hot Shot 2 to this system. Around 1 to 2 oz to the 14 oz system.....will let you know if that is the fix.

Thanks everyone for your input especially BayouRunner.


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## DanS26 (Oct 25, 2012)

Finally found the problem.......light in the freezer stayed on 24/7 due to defective door switch. Light was injecting heat into the system causing large temp swings and long cooling cycles. 

I wasted a lot of energy in the last two years because of this problem, but the sealed system on this SubZero keeps chugging along. 

Thanks everyone for your help.


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## Druidia (Oct 9, 2011)

Even with the door switch fixed, you could probably also consider changing your fridge/freezer bulbs to LED.


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## DanS26 (Oct 25, 2012)

OK guys....all you DIY'ers and maybe some of you appliance repair techs will appreciate this.

If you have read through this tread you realize that I have been trying to repair a 37 year old SubZero built in refrig 211RFD. For the last 2 1/2 years I have been battling a large temp variation in the unit. I replace just about every part available but no improvement. I researched every possible explanation for this temp swing.

As I explained a few posts above the problem was a 40 watt appliance bulb being on 24/7 in the freezer unit. I thought initially the problem was the switch and I blamed the switch. But after replacing the switch, I tested the switch and found it to be functioning fine.

The real culprit was the the 2" x 2" small metal plate that pushed the switches in when the freezer door was closed. Yes, the fix was only to bend the metal plate a small amount toward the freezer compartment. Somehow the plate was bent ever so slightly backward so that the plate did not push in the switches enough. 

I'm just posting this to close the loop. The solution was to bend a metal plate approximately 1/4".


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## DanS26 (Oct 25, 2012)

Druidia said:


> Even with the door switch fixed, you could probably also consider changing your fridge/freezer bulbs to LED.


Took your advice and replaced all the appliance bulbs in my SubZero and also in my bulk freezer.

Used these parts:

https://www.amazon.com/gp/product/B00UJ6PGEU/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B018QMDXT8/ref=oh_aui_detailpage_o09_s01?ie=UTF8&psc=1

Thanks for your suggestion. Better lighting and 10 times less power and heat. (4 watts vs 40 watts)

Just a follow up on my 37 year old SubZero.....it is running like a brand new machine. Of course I've replaced about every moving part and a lot of the non-moving parts.


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## Koa (May 13, 2017)

DanS26 said:


> Took your advice and replaced all the appliance bulbs in my SubZero and also in my bulk freezer.
> 
> Used these parts:
> 
> ...


Just curious about your bulb base size since you show a link to an adaptor which looks like your subzero takes a medium base and you're adapting it down to fit the smaller E17 LED base. Is that correct? I thought your SubZero took the E17 base bulbs, but it's been awhile since I looked.

If you do have medium base bulbs, I've been using the GE LED Light Stick bulbs in my refrigerator for over a year. It's not a SubZero and I had to cut down the lens so it would fit. Your SubZero has more room for the bulbs.

Home Depot (in store) is closing out on them at the moment for $2 a three pack.

https://www.amazon.com/GE-Lighting-...qid=1495732450&sr=1-1&keywords=Ge+light+stick


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## DanS26 (Oct 25, 2012)

Koa said:


> Just curious about your bulb base size since you show a link to an adaptor which looks like your subzero takes a medium base and you're adapting it down to fit the smaller E17 LED base. Is that correct? I thought your SubZero took the E17 base bulbs, but it's been awhile since I looked.
> 
> If you do have medium base bulbs, I've been using the GE LED Light Stick bulbs in my refrigerator for over a year. It's not a SubZero and I had to cut down the lens so it would fit. Your SubZero has more room for the bulbs.
> 
> ...


Yes, this older SubZero uses the standard base. I probably should have gone with the bulbs you recommended, but done is done and these small 4W LED's seem to put out enough light in this smaller unit.


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