Subzero 650 ices up in high humidity, above the crisper

[matt]

I have a subzero 650 which works great except in the summer during high humidity.  I get iced up coils...  icing is behind the aluminum back panel, around the evaporator coils (NOT down under the crisper drawers)  I have to pull out a heat gun and defrost 3 times a summer.  A pain.  Is there any way to increase the frequency of the defrost cycle?  any other way to get around this issue?   Local subzero person will Not work on the machine because I got it from a secondary source.   Love this frig  EXCEPT for this giant throwback pain in the butt problem.  thanks

[Hiroshi]

If the frost pattern is a teardrop shape at the lower left (right above the bottom shelf), then you likely need a small blast of refrigerant on the fresh food side of the sealed system. These machines are also extremely sensitive to dust on the condenser coil because the two compressors share the same condenser...

[Hiroshi]

I almost forgot to mention... There is no defrost system on the Fresh Food evaporator, that is why frost being present on that coil is indicating a deeper problem- the defrost timer in the machine compartment applies to the freezer only!

[AccApp]

The permanent solution to your problem is at least a new evaporator and filter/drier but ideally a new compressor and heat exchanger as well. You are losing refrigerant and the frost will get worse before it stops cooling altogether. With a leak of this nature it can also pull in moist outside air which will contaminate the POE oil in the compressor, There must be another servicer nearby who can help you.

[matt]

The icing is uniform across the coils and fins from left to right including the coil that has no fins on the left and on the right.  Ice is more heavy at the bottom, sort of an icicle effect, but it does not extend down.  This issue has occurred for about 4 years, it is not worsening in any way so it is hard for me to reach the conclusion that there is a leak in coolant.   Perhaps I need to take a few appliantology classes but I dont see how having LESS coolant would make more ice.  

 I also have cleaned out the entire upper condenser compartment above the frig so dust build up is not a factor.

Any other thoughts before I go play appliance repairman roulette?

Love this site.   Thx

 

 

[vee8power]

Are there any air leaks in the fresh food compartment? Do the evaporator fan and door switches work correctly? 

Post a picture to photobucket or something and put the link here so we can see what it looks like.

Maybe it wouldn't hurt to put gauges on if there are valves in place and see the temperature that evaporator is running. There is an off chance that it's low on refrigerant without having a leak.

18 hours ago, matt said:

I dont see how having LESS coolant would make more ice.

Pressure/temperature relationship says lower pressure equals lower boiling point.

I think the guy who won't service your unit has other reasons.

[Hiroshi]

Refrigeration is a very counter-intuitive discipline, but it is understandable when explained correctly. The first step is to know the definite meaning of evaporate and condense, and to know why condensing creates warmth and evaporation creates cooling effects. Less refrigerant gas means there is more room for expansion of the compressed gas during the evaporative process- which results in colder temps and more frosting on evaporator coil. The fridge side of your machine is never meant to be at or below freezing. 

 

[matt]

Very well explained.

This now makes sense, knowing that there is no defroster  and that it is not even supposed to be below freezing ... I'm still thinking of the old school units that let the extra cold air go into the frig from the freezer unit.  You knew you were in trouble when an iceberg started in the freezer.

Is it out of line to propose that there is no leak, as the condition has remained constant for 4 years and there is slightly too little coolant in the system?  

This machine was bought from a secondary source.... the Sub-zero repair guy said something about numbers not matching up...and he would not know the exact amount of refrigerant to put in... thus he refused to work on the machine.  So it appears I have a guessing game caused by some hybrid of parts.

Does that make sense?

best way to proceed?  

 

 

[matt]

Seems like I need to get a good technician who is willing to play organized guess and check.  does that make sense

?

[Hiroshi]

If it is pretty stable, that usually indicates a very SLOW leak, therefore on the low-pressure side of the system. Shouldn't take much guesswork, just a tech that carries some guages and a tank of refrigerant- you will want to let them know which refrigerant the unit is using, the model number plate will list either R-12 or R-134a as the gas the machine is using ( and how many ounces it holds), but Sub-Zeros traditionally have a charging valve installed from the factory to simplify the addition of refrigerant. If the new charge doesn't leak out before a year is up, you can keep charging it. If the increased pressure of a full charge causes it to revert to frosting in a couple months or so, you will need the evaporator replaced.

By "the numbers don't match up" does he mean it has a new off brand compressor or sealed system work has already been done? Using the guages, it can be filled without overcharging when the overall capacity of the system is unknown, it will pull vacuum until it is full.

As long as you let the tech know you aren't going to place $10k worth of blame on him if he can't charge it/get it running correctly, you shouldn't have too much trouble finding help

 

[lvasquez11]

Also post a pic of model serial tag.  

Its very important when looking up parts

[BrewHobbyTech]

On 8/4/2016 at 1:19 PM, matt said:

The icing is uniform across the coils and fins from left to right including the coil that has no fins on the left and on the right.  Ice is more heavy at the bottom, sort of an icicle effect, but it does not extend down.  This issue has occurred for about 4 years, it is not worsening in any way so it is hard for me to reach the conclusion that there is a leak in coolant.   Perhaps I need to take a few appliantology classes but I dont see how having LESS coolant would make more ice.  

 I also have cleaned out the entire upper condenser compartment above the frig so dust build up is not a factor.

Any other thoughts before I go play appliance repairman roulette?

Love this site.   Thx   

 

 

On 8/4/2016 at 1:19 PM, matt said:

Is it frost or ice?? Since you've not had it charged or the refrigerant topped off, and it's been ongoing for at least four years......I have two options I'm leaning toward....although it could be something else.......my first two guesses/opinions would be........#1.....it's undercharged, and has been since you received/bought it, and has no leak....or very very minor, and undetectable. #2 since this only happens in the summer and in high humidity situations...I'd say you have an issue with a door seal, or possibly warm air going up your defrost drain tube(?, I hate that), or possibly just more use and opening of doors during the warmer weather months. I'm leaning more toward it's undercharged........ 

My final answer(maybe, unless I'm offered a beer or two)....I'd say undercharged, and it's just running much longer in the warm weather months. Doesn't mean you have a leak......it could've been undercharged at the factory, and that's the way it's always been. Kinda reminds me of a Carly Simon song of the same name, or something close.......yeah, she was pretty hot back in the day......and I'll have an IPA now.....dealers choice....ummm.....or whatever....

 

On 8/4/2016 at 1:19 PM, matt said:

 

 

[AlboGator]

8 hours ago, BrewHobbyTech said:

The icing is uniform across the coils and fins from left to right including the coil that has no fins on the left and on the right.  Ice is more heavy at the bottom, sort of an icicle effect, but it does not extend down.

Cold control is where I'd go first. They can be hard to pin down sometimes but a frozen evaporator in the refrigerator is a sure sign that it's running too long. As long as the door isn't being held open overnight then you have almost certainly have a bad cold control that's not turning off the cooling system when it reaches temp. 

[BrewHobbyTech]

4 hours ago, AlboGator said:

Cold control is where I'd go first. They can be hard to pin down sometimes but a frozen evaporator in the refrigerator is a sure sign that it's running too long. As long as the door isn't being held open overnight then you have almost certainly have a bad cold control that's not turning off the cooling system when it reaches temp. 

I'd agree with the bad cold control except for the fact that he stated that it only does this in summer heat and it's been ongoing for four years. Only way to tell for sure is to put a set of gauges on and read the internal pressures. I'm sticking with my diagnosis of it being undercharged, not a lot but enough so it can't keep up with the higher load in the summer, therefore running all the time, which would mimick a bad cold control. 

[AlboGator]

5 hours ago, BrewHobbyTech said:

I'd agree with the bad cold control except for the fact that he stated that it only does this in summer heat and it's been ongoing for four years. Only way to tell for sure is to put a set of gauges on and read the internal pressures. I'm sticking with my diagnosis of it being undercharged, not a lot but enough so it can't keep up with the higher load in the summer, therefore running all the time, which would mimick a bad cold control. 

I don't think so but it's not my eyes/hands that are on it to confirm. Gauges would help for sure though to eliminate or confirm because that's the first thing I thought of and even went back and removed the first comment. Based on him saying that the ice has formed top to bottom, left to right it couldn't possibly be a low charge although that's what I thought at first. I think that it's coincidental of the summer time heat or could be a bad evap fan or door switch provided the condenser is clean. Those are easy to check though. 

[BrewHobbyTech]

On 8/11/2016 at 7:10 PM, AlboGator said:

I don't think so but it's not my eyes/hands that are on it to confirm. Gauges would help for sure though to eliminate or confirm because that's the first thing I thought of and even went back and removed the first comment. Based on him saying that the ice has formed top to bottom, left to right it couldn't possibly be a low charge although that's what I thought at first. I think that it's coincidental of the summer time heat or could be a bad evap fan or door switch provided the condenser is clean. Those are easy to check though. 

Hey bro........I'll only agree with what info was posted..........it's most likely either a bad cold control(what you said), or what my diagnosis is.......if the OP posted everything as accurately as possible......and truly is accurate.......my diagnosis is the most likely......LOL......but you could be correct, it is possible...........

I'll bet you a six pack or a four pack.......of your favorite brew. I know you're posting bud light as your favorite brew, but you can choose an expensive beer, and many come in four packs........just saying, and just in case you're right. If I'm right I won't actually want to collect anything, so you have nothing to lose if you want to take on the challenge........I don't care either way, I just want to know what the actual problem is/was. 

.......I'm pretty sure I'm right(90% sure.......if the info given is accurate, and without me actually being there to see for myself).............LMAO........

Obviously you know refrigeration, so I'm not questioning that.....this is just friendly stuff......

 

 

 

 

 

 

[BrewHobbyTech]

On 8/11/2016 at 7:10 PM, AlboGator said:

I don't think so but it's not my eyes/hands that are on it to confirm. Gauges would help for sure though to eliminate or confirm because that's the first thing I thought of and even went back and removed the first comment. Based on him saying that the ice has formed top to bottom, left to right it couldn't possibly be a low charge although that's what I thought at first. I think that it's coincidental of the summer time heat or could be a bad evap fan or door switch provided the condenser is clean. Those are easy to check though. 

Have to add this.....just to add what I forgot and wanted to mention first....or whenever. 

 

On Sub Zero refrigerators(not sure on the newer ones) the cap tube enters the top left side of the evaporator in the ff section. Of course any frost or ice build up would go top to bottom.....and left to right(in its own way I guess). My opinion/diagnosis stands, and is correct, in my opinion.....until proven wrong, which is possible. I believe your original diagnosis, which is the same as mine.......is correct. What I've found in my own experience(s) is that your first intuition/gut feeling/personal experience/knowledge is usually correct. Not all the time but usually. Sometimes it's good to second guess yourself.....but if you think about things too much it can really screw you up. Well, that's just personal experience, it may not be that way for everyone, or for most. Just food for thought........and maybe a free six pack.......LMAO  

 

 

[matt]

I'm so happy to have you all sharing in this fine mystery of the universe.  I have been out of town, and its been super hot n humid, so I likely will be able to have some photo evidence for you to ponder.   Maybe I should promise you all plane tickets  to RI and multiple 4 packs (upon reaching solution) .  It would be cheaper than  a new subzero!   

[BrewHobbyTech]

1 hour ago, matt said:

I'm so happy to have you all sharing in this fine mystery of the universe.  I have been out of town, and its been super hot n humid, so I likely will be able to have some photo evidence for you to ponder.   Maybe I should promise you all plane tickets  to RI and multiple 4 packs (upon reaching solution) .  It would be cheaper than  a new subzero!   

Cool......after you send the pics and let us all know what the "official" diagnosis is, or what the actual fix was.....you can have AlboGator send me my six pack......LMAO........

[AlboGator]

Pics would help for sure. 

[AlboGator]

Any updates on this? Pictures? 

[matt]

Sorry for the delay... Latest update.  Going on the implied possibility  that there is too little coolant in the system than there should be which is producing sub freezing temps.  I raised the thermostat setting to 43.

 It has been high heat and humidity the usual trouble maker condition for a couple weeks.  I removed rear panel and there was only super slight icing on a few fins, but otherwise looking good.    I have no definitive gauge evidence for the more quantitative frig samurais at this point.

[Koi Guy]

 

If you can provide the model and serial number that would be great. On some models there may be a defrost drain trough heater- which is basically a low temp heater that is taped to the underside of the drain trough. It is there to prevent ice build up on the drain trough. (Note that there is sometimes also a drain heater which is inserted into the drain line.)  If this fails, you may experience ice build up on the drain trough which can be exacerbated in times of high humidy. I've seen your exact same condition because of this. It happened in summer here and Florida and took me three trips to finally identify.

Of course there are some basic steps that should be considered and are easy to check or perform- the condensor coil should be blown out properly (using a simple brush does not cut it, you will be amazed at the amount of dust that comes out if you use compressed air); the condensor fan blade should be clean; the fan motor should run at full speed; check the door seal; make sure the door is striking the light switch and that the light turns off. Assuming all is well, we can move forward into control components and then into refrigeration components.

Personally, I have not seen a condition of low refrigerant causing a sub cool condition. Typically with low refrigerant you will find low cooling. You may also experience an ice ball build up which is easily identified.

[AlboGator]

6 hours ago, matt said:

 I removed rear panel and there was only super slight icing on a few fins, but otherwise looking good.

Top left corner?

[BrewHobbyTech]

9 hours ago, matt said:

Sorry for the delay... Latest update.  Going on the implied possibility  that there is too little coolant in the system than there should be

That's my diagnosis on the info you have provided, it's not an implied possibility. I'm either right or I'm wrong, but given the data you have provided, and with my experience, I believe I am correct......and I'm sticking with my diagnosis until proven wrong. The only way to know for sure is to have a clear, or fairly clear evaporator, and put a set of gauges on there to see what internal pressures you'r reading.......or you can just hook up a can of refrigerant and add some and see what happens. If my diagnosis is correct then by adding refrigerant you'll get a more complete frost pattern on the evaporator. If that doesn't happen then I'd say you probably have a restriction.