I have been reading past posts here trying to study up on a model year 1992 Sub Zero 590, serial number M960991. It was bought new, placed within custom cabinetwork, and has been running since. In terms of major repairs, the freezer compressor was replaced in 2010. The year of manufacture on the replacement freezer compressor is 2009.
Last year there were bad water leaks. A technician diagnosed and replaced the dual water valve. Leaks persisted but not from the valves. Last winter I moved it to another spot as the wood floor was getting damaged. Since the 590 has been in its new location, I have started trying to put time into it. I found and cleared a clogged fresh food evaporator drain line that was causing puddling on the floor. That stopped the last of the water leaks, making it now possible to move the 590 back to its spot in the kitchen.
As a last step before moving the unit back across the room, I thought to look at the non working icemaker. The icemaker stopped working within the last year, and had been serviced before. I found this site, read and learned, and got the icemaker replaced. I verified all the internals of the new icemaker were working and that the icemaker water fill valve was working. Still no ice production. Troubleshooting tree pointed to "verify freezer temperature is below 10degF." It was not, and this is when trying to fix the icemaker grew into looking into the freezer's state of health.
There was one of these in both the fresh food compartment and the freezer. The mechanical thermometers would show a rise each time I opened a compartment door to read the gauge. I bought one of these and now keep an eye on the temperatures with the doors closed.
Before looking into the icemaker, I did not think the freezer had any major problems. After watching freezer temps on and off again for the past week or so, it seems the freezer technically gets below freezing but not to the listed setpoint in the factory manual +4/-6 degF cut-in/cut-out. The thermostat on the old icemaker was marked for 15 degrees Fahrenheit. I only had the mechanical thermometer at that time - and later learned the two identical mechanical thermometers disagreed with each other by 5 degrees at room temp - but the old freezer thermometer showed the freezer only getting down to 18degF (infrequent sightings of 10degF). I think the freezer was getting cold enough that it seemed alright and seemed to freeze food, but was not cold enough to satisfy the new [capable-of-working] icemaker. I checked that the evaporator fans on both sides were working, and they did power on and spin up each time I simulated the door closing by pressing the fan switch. The condenser was also vacuumed (light accumulation of dust). The freezer door closes well and the freezer door seal is in good condition. The fresh food refrigerator door does not close equally well (standing in front of it, doors closed, the top left corner of the refrigerator door seems tweaked out, away from the refrigerator a bit (this is where it is typically grabbed to be pulled open)) as the freeezer, but does close and seal. There are two tiny square patches worn away (they do not stretch to the top or bottom) where the light and fan door switches touch the door seal a bit right before the plastic tab above the seal on the door pushes them closed.
All food was removed, pictures were taken of evaporator coils, unit was unplugged and the compressor compartment covers were removed for inspection. I learned the dual water valve had been replaced with one that would not bolt up to original mounting holes, the freezer run capacitor was not wired in, the freezer compressor ground green wire was cut off and tucked underneath a wire bundle, the replacement freezer compressor model number ( Embraco FF 8.5BKW ), the freezer compressor Neutral wire termination was bad ( seemed like most of the individual wire strands were cut and frayed away, only a couple strands going into the crimp ) where it plugged into the overload protector, the end of the Neutral wire (close to the bad termination) was discolored and stiff, defrost timer was turning, condenser fan was spinning but dirty and leaning forward towards the condenser, rear two mounting studs of replacement freezer compressor were missing top nuts.
Please see attached for pictures of evaporator frost patterns. They are not from the same time. When I shut the unit off and took the fresh food evaporator coil picture (Friday), the freezer evaporator was already defrosted by the time I switched sides and gained access to it. So the frosted freezer evaporator picture is from two weeks ago, minutes before I removed the old, non working icemaker (nonstick coating had peeled away from most of the first ice cube fill area, rear fill area plastics bent, thermostat contacts corroded).
Yesterday I cleaned the compressor compartment area, replaced the condenser fan mounting hardware so it is upright again, blew out the condenser (was already vacuumed) from the compressor side (forcing air in the same direction as normal vacuuming from the air intake side), straightened all the condenser fits on the air inlet side, tested the freezer compressor starting relay and overload protection module, replaced the bad neutral wire termination and crimped a new terminal on the previously cut freezer compressor ground wire. I put the evaporator covers back in on both sides, put some half full water jugs in the freezer for ballast, left the refrigerator empty, plugged the unit back in and turned both cold controls up to 5.
I had hoped to have a similar experience that another person with a 590 posted elsewhere. I got an error when I included the link but the end result from that person's condenser cleaning efforts was: "OK, I'm back, and better educated. I vacuumed and blew out the SubZero 550's condensor coils for about a half-hour, and I was amazed at just how much debris kept coming out. ONce I was finished, I emptied the freezer, and it cooled down to zero degrees over a few hours. It has been staying there for a week now, with the control set at 3 to 4. The icemaker is also working just fine."
It has not been 24 hours yet, but the freezer did not show a dramatic improvement in performance. Last night, when I first turned it on, it seemed promising as it came down quickly from room temperature to 49degF before I left, but this morning it was only at 22, with a recorded low of 18 at some point during the night. As of 2:15PM (now), it is down to 14degF, having come slowly down maybe a degree every two hours. The freezer door has been closed since last night. The refrigerator temperature appeared sluggish last night but seemed to gain momentum after a few hours, and today, at present it is at 39degF. It is empty, but that seems close enough to the setpoint listed in the manual for a "normal #5 [cold control] setting" of 37/35 degF cut-in/cut-out. Maybe it will work better after the extra compressed air blowout yesterday, but after vacuuming the condenser last week, the refrigerator continued its usual behavior of getting to its temperature setting overnight, and falling behind during the day as the door is opened and closed for regular use.
Freezer compressor was showing 3.3Amps current draw two days ago. Only locked rotor amps are shown on the Embraco nameplate (sticker) so I am not sure what is is supposed to run at. The SubZero 590 manual lists 1.4Amps but this is not the original compressor (though I would think it would be closer / more in the ballpark, than close to double). I have not measured the refrigerator compressor, as this started as a "why won't the freezer get cold enough for the icemaker" question. Thursday night, before the unit was unplugged for inspection, the freezer did peak low enough to satisfy the icemaker and make ice all night. (Seems like a side note now.)
I did not check the defrost heaters as I thought shutting the unit off and turning it on would give the unit an opportunity to see if it could reach 0degF from a zero frost (room temp) starting point. I did not adjust the defrost timer so it's possible that when I powered the 590 back on and set the freezer control to 5, it ran into a defrost cycle (time-wise) before reaching its full potential.
I see that I may still have to rule out bad defrost heaters. If the heaters are not a problem, given the test performed so far and data presented above (and pictures attached), are there any advisable repair options for this Sub Zero 590? Any constructive advice would be appreciated as a possible very large financial decision seems to be coming up. From reading past posts on appliantology, it seems that coordinated replacement options are preferred so a sealed system can be made almost new. Post #11 mentioned $1000 to $2000 for a guesstimate. Would I be in the ball park of right to assume that both sealed systems are due for replacement? I'm curious if this 590 could be fitted with replacement new condition sealed system components that could reasonably be expected to provide four or more trouble free (mostly) years of service. I have looked at a 48" counter depth side by side unit previously made by Samsung for $6000 and have not yet sourced specific cost figures for a replacement Sub Zero unit (though I am told it would be between $10000 and $13000).
Thank you for taking a look.