I have a typical household setup: Freezer on top, fridge on bottom. Do such devices usually all feed out of one big Freon coil network on the bottom unit (fridge bottom,) or are they two Freon coils - one on top with the freezer, one on bottom with the lower fridge?
If they are all feeding out of one big Freon loop, how does the freezer attain a colder temperature than the fridge?
Generally, only the freezer is cooled.
Air is then circulated from the freezer compartment to the refrigerator compartment and back.
Usually the evaporator coil is in the freezer, which is where something like 90% of the cold air is blown through. There’s just a small vent into the refrigerator, so even though it’s dumping the same 0ºF or colder air into the refrigerator, it’s not dumping enough of it into there to make it freeze. The thermostat is in the refrigerator, because it’s important that it not get below freezing, and it requires more careful control and less swing in temperature. The dial in the refrigerator controls that thermostat, say somewhere between 34ºF and 45ºF or something like that. The dial in the freezer only controls a damper on that small vent that passes through into the refrigerator. Setting the freezer dial to colder closes the damper more, so it takes longer to cool the refrigerator, leaving more very cold air in the freezer.
Because of the thermostat placement, if you have a lot of items to freeze, and you need them frozen quickly, you don’t want to load them up in the freezer and never open the refrigerator door, especially if it just shut off. The thermostat in the refrigerator has no way of knowing that you just put a bunch of warm stuff in the freezer. Conversely, if you put something warm in the refrigerator, you may find that your ice cream is now hard as a rock. It’s really no different than blasting a window air conditioner in one room with the door almost all the way closed, allowing a little bit of air to spill into the next room. The critical part is having the thermostat in that other room. It’ll work out ok until you introduce large changes in the load, such as turning on a bunch of lights or putting several people in one room and not the other.
Generally only very high-end refrigerator/freezers like SubZero have completely separate compressors and evaporator/condenser coils. I’m not sure if there are ones that have a single compressor and condenser coil, but separate evaporator coils and expansion valves. That’s common in air conditioners (such as ductless mini-splits and larger commercial units), but that might be too much mechanical complexity for a residential refrigerator.
Ah OK, thanks. Where are the Freon loops usually located?
On the back wall, behind a plastic plate. Maybe on the top in some models. They are protected, because they are covered with delicate fins or spines.
Ah OK - so the back of the top freezer, basically?
If you post the exact make and model, I can look it up for you…
General Electric GTH18CBDELWW
there’s only one refrigerant circuit. the condenser coil is underneath the unit, along with the compressor and condenser fan. The evaporator (chiller) coil is in the freezer compartment probably behind an access panel with the circulator fan.
https://www.appliancepartspros.com/unit-parts-parts-for-general-electric-gth18cbdelww.html
Samsung make much of “Twin Cooling” on their more upmarket side-by-side models, but they still only have a single compressor. The clever bit is just a more sophisticated air circulation and temperature sensing system.
let me start with nit pick. Refrigerators today seldom contain freon. DePont’s patent of refrigerant gasses expired years ago.
I have a Kitchen Aid refigerator. One compressor, one condenser, but 2 evaporator coils, 2 evaporator fans and 2 thermostats. Each evaporator fan is controled by it’s thermostat. One for the freezer and one for the cold box.
Having fought, years ago, with a fridge where the defrost timer died and it always iced up, I had tot ake it apart to let the cooling fins defrost manually (with a little help from a hair dryer) about once every month or two…
In a modern defrost fridge with freezer on top: (OK, in some models they may be on the back wall of the freezer compartment) The cooling coils, with fins like a radiator, are between the freezer and the fridge. They are surrounded by Styrofoam. I unscrewed the bottom plate of the freezer compartment, lifted out that metal base and a thin (1 cm or so) sheet of foam, and there wwere the S-shapped coils and fins.
Basically, there’s a fan to blow cold air over the coils/fins into the freezer compartment and another fan to blow air into the cooler compartment. Each fan is separately thermostatically controlled. Every so often the coils are heated instead to melt any accumulated frost - hence the “defrost” capability. Melted water runs out of the cooling coils (which sit in a foam tray) and down a tube from the back of the fridge to a pan sitting under the fridge where it (should) evaporate. obviously during the defrost the fans don’t run, don’t blow hot air into the fridge.
Problems -
Water in the fridge bottom - the drain hole in the coils is plugged, defrost water overflows into the fridge. If you are lucky, you can pull out the fridge, pull the small plastic tube off the back and unplug the drain with a pipe cleaner.
Fridge slowly stops cooling: likely the timer unit (used to be mechanical) has stopped turning, fridge never defrosts, eventually the whole cooling coil fins become a solid ice mass. Replace the timer. With a solid mass of ice, the fans cannot blow air (or enough air) to properly cool the compartments.
Fridge becomes an oven: I had a friend with this problem. The defrost timer died during the defrost cycle. The fridge was stuck on heating the cooling coils. Replace the timer.
Fridge won’t cool: If you are lucky, fridge is unplugged. Otherwise, if the compressor is running, there may no longer be freon. Likely after a while this will burn out the compressor. If the compressor is not running, maybe the motor died. Anything wrong with compressor most likely means - Time for a new fridge.
IANAApplianceRepairGuy - but AFAIK the compressor units cannot be repaired, and nobody is going to refill freon in a fridge (especially an old one) without extensive tests to determine why the freon leaked. There are fancy new safer “freon” compounds, but the type seems to change. When my house A/C died, they did not have the same compound to refill something made 13 years ago, I needed a whole new unit. Plus it was good money after bad if they had to do an extensive leak test.
Never had a fridge with an internal fan. (Top freezer units don’t need a fan). “Freon” is not in use anymore. But wanted to add –
when you put your old refrigerator in your garage, if your garage stays cold enough to keep the refrigerator cool, it will never run the compressor, so the freezer compartment will thaw out.
Yes, there are modern freon substitutes which are AFAIK, still chlorofluorocarbon concoctions, just less atmospherically lethal. As I mentioned, when I had to replace my A/C unit a year ago, they mentioned the fluid that was used 13 years ago was no longer approved or available. So there have been numerous iterations of these substances.
There may be many different configurations of refrigerators. The trouble with cooling the freezer directly with the coils, is that at times the defrost cycle will expose the freezer to heating as the cycle is reversed and the coils/fins heated - hopefully not long enough to thaw things.
My mini-fridge is not frost-free- it’s basically a small freezer compartment which has the cooling coils embedded, inside top of the fridge compartment. The theory is running enough to cool the rest of the fridge also keeps anything inside that small metal compartment frozen. The thermostat sensor is in the air underneath the freezer. Every few weeks, you may need to unload everything and let the ice buildup melt off the freezer box.
I’ve never seen a full-size refrigerator/freezer that DIDN’T have a fan, over/under or side-by-side. All the over/under ones I’ve ever had have fans. These are all cases where the evaporator is buried either behind the rear freezer panel or in the floor of the freezer. In smaller under-counter or dorm fridges where the “freezer” is inside the main cabinet but it’s just the evaporator made out of a stamped piece of metal in the shape of a shoe box with a little plastic door then yeah, that doesn’t need a fan. That’s how it is in the USA market anyway.
Regarding Freon, yes it is technically the trademarked name of refrigerant R-12. However it apparently also applies to R-22 and also R-410A as manufactured by Chemours, along with a couple of other lesser-known refrigerants. R-22 was sometimes referred to Freon-22 while R-12 was called Freon-12. I’ve never heard R-410A referred to as Freon though, just Puron as branded by Carrier or Genetron by Honeywell. All that said, this is just a pedantic argument. Colloquially Freon is used to refer to all refrigerants. It’s become something of a proprietary eponym or genericised trademark like Kleenex, Band-Aid, Velcro, Xerox, Photoshop, and Google.
Those are mostly correct. Some drains can be tricky to unplug.
Occasionally a defrost element breaks or burns up and the unit will ice up. I would ohm everything out first, then advance the timer to defrost and see if it pulled current–let me know if it was the element or the timer.
Occasionally a timer would stop in defrost mode–the fridge would seem dead, get warm and not run. Turn the timer dial by hand and it would start.
One common problem I had on fridges that wouldn’t cool was condenser fans that stuck/blocked/burned out. Or else the current relay was bad for the compressor, so I’d put a “hard start” kit on them.
I used to be an appliance repair guy. Compressors can be repaired or replaced, but it’s not worth it in 99% of the cases.
I’m surprised at the Fridge becomes an oven–there’s a defrost thermostat that opens up when it gets warm enough. In your example, both the defrost thermostat and timer would have to be bad. Certainly could happen.