Assessing the cause of freezer coils icing up

Question

We have a 6 year old Frigidaire upright freezer (around 17 cu ft). It suddenly stopped cooling, even though the compressor was running, and it was producing puddles of water on the floor. I thought it might be just icing up, so I unplugged it for a day and eventually, the dripping stopped. I plugged it back in and it appears to be working normally.

I'm aware that low refrigerant can cause it to ice up. However, it's a totally sealed system, with no connections for testing or refill. Which leaves a number of expensive possibilities if there's still a problem:

• Fill it up again with food and possibly lose another batch of food.
• Get it serviced, which would run about half the cost of a new one.
• Replace it.

So my question is about trying to determine whether there is still a problem.

• Is it usual or typical for a freezer in normal working condition to build up ice on the coils over time from house humidity, or does that happen only if there's a problem, like low refrigerant?

  I kept it at the maximum cooling setting, which produced a temperature of below minus 10 degrees, which is colder than a normal freezer setting. Could this have contributed to its icing up?

• If the problem is low refrigerant, best case is that there was always a minute leak and it took 6 years to lose enough to cause this problem. However, that means even if the rate of continual loss is tiny, it's already at a low point, so it would be expected to ice up again.

  If the refrigerant is low enough to cause icing, how fast does that occur? For example, If I just run it empty for awhile to see if it ices up again, what order of magnitude of time would be a reasonable confirmation that it's OK (days, weeks)? Or is that too variable to be a useful test?

• Is there anything else that can be checked without specialized refrigeration testing and repair equipment that would indicate whether the system is not running normally?

Answer 1

Like the OP said. "It's a sealed system." If it was a leak it wouldn't "remove heat" at all. (fridges don't cool, they remove heat.) Automotive AC's DO leak, slowly, because they use rubber hoses/lines. So forget about the "low refrigerant", that ain't it.

The problem is one of three things. First (and most likely) the defrost timer. It's usually located in the plastic housing in roof of fridge compartment. Look for a larger hole that does not have a Phillips screw in it. Use a flathead screwdriver to turn the flat head looking plastic piece you'll see inside that hole. It's like a timer you use for your Christmas lights for example. Turn it until you hear a loud "click". Listen for your compressor/motor to turn off. If after about 5-10 minutes your coil starts dripping water/black heater coil bar gets hot (the header runs along coil; don't touch it, it gets real hot) then your timer's shot. Go online with your fridge model number and order that cheap part. Remove the screws that hold that plastic cover on, unplug the old put in the new, WITH THE FRIDGE UNPLUGGED. Turn the new timers screw until 2 clicks when u install it so it's in cooling mode.

If it does not heat up it's probably the defrost thermostat (a little disc mounted by coil.) Test with multimeter. It should have continuity when it is at freezing temperatures and should change to open circuit when the temperature rises above approximately 37 degrees F.

If that checks out then it's the heating coil rod. Double check the timer/thermostat before concluding it's that because it's a bit of a job to replace and least likely problem.

There is also a slight chance that it could be cause by a bad door gasket but you won't see major solid freeze up, just excess, making the unit work harder and run longer than it should. Here's a decent video on this issue. https://www.youtube.com/watch?v=2kNfNfHTgCo He does keep calling the timer "the thermostat" but corrects himself in captions.

Answer 2

It is probably low on refrigerant because of a leak somewhere in the sealed system. Just because it is a sealed system does not mean it will not leak. During the "normal" building process one of the builders was probably not having a great day (not enough sleep, poor instructions, or too much wine the night before) so he did not do his job correctly. You will have to make a decision to have it serviced of replace it. Most stuff today is made to be replaced not repaired. We now live in a "replace", don't fix society.

Answer 3

Well, I can offer a data point for anyone else in the same situation. I just let it run with nothing in it to see how it would behave for at least the first few days. Within a few hours of plugging it in, it reached the expected temperature. Then over the next day and a half, the temperature rose 40 degrees. So at least in my case, letting it run for less than two days was long enough to demonstrate that it's malfunctioning.