Was running long, now constantly cycles

Refrigerator & Freezer Repair
1

I have a Frigidaire/Electrolux FFHT1826LB0

For the past three or so months, the refrigerator has seemed to be running much longer than it normally does, though it was not getting abnormally cold.

Last week the freezer door was knocked open by off balance food, and when I found it the next morning, a good deal of the freezer had thawed, and ice crystals were all over the food in the back.

I cleaned up the mess, rearranged and closed it.

Now it seems like the defrost timer isn’t turning off for a cooling cycle. The refrigerator will run for about 3 minutes, and then turn off for about 5 minutes, then run for 3 minutes again, repeatedly. (This is a slightly longer run duration, now that I have cleaned the condenser coils.)

As far as I can tell, the motor is not overheating. It is hot to the touch, but not uncomfortably so. There is a clicking sound relating to the power cycling, and it seems to be coming from the back right side, somewhere near the freezer. That is the general location of the Defrost thermostat, as well as the defrost timer.. however, I can’t see any easy way to access the defrost timer.

Any ideas are welcome, I don’t cherish the idea of taking the entire refrigerator apart, but that only more so than buying a new fridge.

2

Your defrost timer is in the top center fresh food compartment behind the control knobs. It may have a access hole to turn it manually but I don’t think that is what you are hearing. I’d guess the compressor is cycling on the overload. That is mounted on the compressor.

If the clicking is predictable pull the rear cover off the outside back bottom and see if the noise is coming from down there where the compressor lives. A bad overload or capacitor is a possibility. However if you are correct in thinking it had been running abnormally long to remain cool there may be a deeper issue with the compressor that is now causing the comp to trip it’s overload. You can test this if you unplug it for 2-3 hours and see if the problem returns after being re-energized. The time off allows the comp to cool and pressures to equalize so the comp isn’t working against a 100 psi high side pressure when it starts.

A quick explanation of your unit is that the cold control in the fridge runs everything. The freezer has no temp sensing at all. If the fridge needs to be cooled the cold control senses that and makes a connection to run the compressor. Since all cooling happens in the freezer the assumption is that the freezer is cold enough when the cold control in the fresh food compartment is satisfied. The defrost timer either measures compressor run time or just a fixed time (12 or 24 hrs for instance) and periodically kills the compressor and turns on the defrost heater behind rear freezer panel.

3

The popping is heard from the bottom, back, right corner of the the freezer compartment, top right back of the refrigerator compartment. The only sensor I would expect to be in that area is the Defrost thermostat, if the timer is behind the main thermostat. The click is a very different one from the main temperature control, and operating that does not manually turn the compressor/fans on. While I was cleaning the condenser coils, I monitored the compressor through several cycles, and even from the back side of the refrigerator, the click is coming from the upper left (as viewed from behind) portion of the refrigerator, not the compressor itself. From what I could see on the schematics, there isn’t an over pressure cutoff outside of the compressor, and when the compressor shuts off, so to the internal and external circulation fans. While playing with the main thermostat, the compressor did enter a “high pressure timeout” period where the circulation fans continued to run, while the compressor did not. After about 1 minute, it restarted and the cycling resumed as previous. After sitting for a day, the freezer is definitely plenty cold, and the refrigerator is cooling. I had tweaked with the air gate between the freezer and fridge compartments, but it is set where I had it previously. I will try to dive into disassembling the temperature controls and possibly the evaporator shrouds Tuesday evening, and see if there is a mess of Strawberry syrup gumming something up there. I would agree that a 3 min on, and 5 min off run cycle is way too fast for the defrost timer, but that is the only thing that I would logically guess to be making these symptoms. I can’t say I’ve heard the sizzle of water on the defrost heater /all that often/, but I have heard it before on defrost cycles, and I haven’t heard it any time since the thaw.. that doesn’t mean it hasn’t ran a defrost cycle though. The internal circulation does blow a good amount of air, I wouldn’t immediately point to an iced over evaporator.

4

Well, I emptied the freezer and took the back panel off, revealing the evaporator… it had significant chunks of ice in it, with significant space around them. It seems to me that it had been frosted over solid at one point, and had semi defrosted at some point before freezing again, but there didn’t appear to be any recent build up of frost. Each time the compressor shuts off, the frost on the tubes would melt away nearly completely, the chunks remaining. I would guess that how ever much it defrosted, was not enough to fully defrost it. However, I have my suspicions that the defroster element might have given up the ghost, or the defrost thermostat is malfunctioning in some way. Really though, how many ways can a thermally controlled on/off switch malfunction? Not a lot. I cleaned more strawberry juices out of stuff, (which was surprisingly minimal at that depth) and melted away the remainder of ice with my heatgun on low. I put it back together and loaded the frozens back into it and went to bed. The next morning, it seemed to not be cycling oddly anymore, however, over the last few days, it seems to have gotten back into that routine of a few minutes off, a few minutes on. I think I’m going to have to test the defrost timer, the defrost thermostat, and the defrost element, to make sure they’re all working correctly. A light across the defrost thermostat should do the trick there, a wireless thermometer would be good on the coils.. I haven’t been able to find any information on what resistance the Heating element should run at, I have tested it, but my meter was reading in the MegOhms.. much higher than I expected.

It would also be nice to know what temperature the defrost thermostat is supposed to open and close at.. Elsewhere, I was able to find that the timer is 6h/21m, though every circuit diagram I’ve seen, makes no indication which poles of the relay are switched, only that there is a connection between two… Bad form.

What bugs me, though, is why is the cycling so short? it’s like a jet of frozen air is hitting the thermostat directly, causing it to quickly cool to shutoff, then warm up quickly to start again.. time to mess with the top/bottom air mix and see what radically changing it will do.

I wonder if I have too much stuff blocking return airflow from the freezer into the evaporator.. that could possibly do the same thing, but it’s never been a problem before…