Good day,
The bi-metal or also called a limiter or defrost thermostat is wired in series with the main heater.
When the timer switches the machine from the running mode to the defrost mode, it shuts off all cooling and turns the main heater on. This could be anywhere from 21 minutes to 35 minutes. The bimetal is a thermostat. It shuts the main heater off when the coil reaches approx. 50 degrees. Without it, the machine would get extremely hot, defrosting all the food, and in some cases even begin to melt plastic parts in the freezer compartment. It's also a safety device, in case the timer went into defrost and failed there. Without it, it would totally destroy the machine, even to the point of creating a possible fire hazard.
Testimonial: "Thanks for the info. When I took the freezer section apart I had to use a hair dryer to remove the insulation as it had chunks and sheets of ice attached and imbedded in the evaporator coil. All meat though especially in bottom of basket had defrosted and ruined. I turned timer to defrost and heater coil began heating up. Fridge and freezer not cooling as cold as used to. Looks like bimetal thermostat and heater working. Could it be bimetal thermostat not turning off soon enough. But why would evaporator core be freezing but ice container which is on front door of freezer is thawing ice and will have water in it from melting. "
Sounds like a timer acting up. I'd change it but it is common practice to relace the bi-metal as security, since it's a flaky part and somewhat inexpensive. The styrofoam must be whole and intact. Everything effects everything else in a refrigerator. Detail is critical.
Reading your response more closely, I can see other issues. Here's the list.
If the fan motor in the freezer is running slowly it could cause your problem.
On older Frigidaires they use switches on the doors to turn the fan motor off when the doors are opened, many on the fresh food door as well as the freezer door. If they are not working properly, or the door is not depressing them same results.
If your model has a box coil and fan motor rather than a vertical stagnet wire condenser running up the back, then that fan motor running slowly or the box condenser plugged with dirt same thing.
If it has a boxed coil, it CANNOT be vacummed out. It must be blown clean with compressed air or a good shop vac. I Know ugly but necessary.
Well, 22 degrees isn't even close. You cannot check the fan switches by hand, the machine has to do it. Place your ear up to the mahine when it is running, and close the door more than once. You should hear the fan motor spool up.
As well, the fan motor in the freezer must not only run, but run at speed.
Take a good look at your insulation. If it is out of place, it can block the air from circulating properly.
Ice, unseen can cause the same problem and worse yet is unseen.
Sometimes when all else fails, shuting the machine down for 24 hours will address that problem.
The thermostat if it doesn't allow the machine to run long enough, can cause the problem. You can jump out the leads to it, and let the machine run continuesly for let's say 5 hours for a test.
The bi-metal can fail closed causing overheating but if the timer goes back to running, it would recover in an hour or so.
Lastley, outside chance a valve is floating in the compressor, not allowing it to pump properly.
Uncommon on older Frigidaire's but .....
I've worked on a ton of frigidaires but that tstat on the right is something I can't recall. If you can get the model number off the machine, it was usually a metal tag riveted to the front or rear rail on the bottom.
They were also good at simply painting the model number on the back in black paint.
Some older models used a second fan motor to pull the air from the freezer into the fresh food compartment. They were controlled by a thermostat.
Take a good look across the top where the controls are, as well as any place on the back wall including behind the crisper drawers.
Last place to look is in the freezer compartment, on the back wall near the top.
Your right about the top getting too cold. All refrigerators that have the main thermostat running the freezer section must have a second fan motor or damper to control the fresh food compartment.
Sorry, model number did not come up. Frigidaire built a lot of and some very strange systems. Pretty old machine. That tstat in the upper right should be the control for the second fan motor. If the fresh food section gets too cold, it could be at fault.
My suggestion now, is to go to a decent sized appliance parts house that deals in Frigidaire, and see if you can be allowed to see an expoded view as well as the temperature range of both tstats.
Tstats aren't AC or DC, the're simply switches. Not unlike the switch that turns your lights on in the house. All circuits are AC, and if the thermostat contacts are closed (asking for cooling) you would read nothing across them.
Forgetting that for now,
If the feezer is 25 degrees and the food compartment is 28, that's bad. The fresh food temp should cycle between 35 and 40 degees.
If it's running at 28, it's stealing too much air from the freezer.
It's obvious the food compartment is way too cold, and is a far larger compartment than the freezer. To add insult to injury, the walls of the fresh food section of any refrigerator have far less insulation R value in them, adding to the issue.
My best guess is get the fresh food compartment inline, and the freezer will retain enough of the cooling, to maintain it's 0 to 8 degree normal temperature.
Good day,
Your close. Refrigerator tstats as they age because of the cam action internally start running colder. It's just a characteristic of these controls.
However, the change is usually gradual and consistent. That Fresh food tstat may be getting bad enough it needs replaced. Time will tell. However, I would look to see if it's available.
Hi Tom,
If it's the motor I'm thinking it is, it's like a lot of strange things Frigidaire does.
You really can't get to the motor shaft to oil it as in a normal motor.
You have to pull the motor, screws should hold the blade on. Then you will see a bronze cap with 2 more screws. When you remove those second screws, the rotating section will drop slightly, exposing a Little of the shaft and a tiny retaining clip.
Don't get brave and try to remove that clip. You'll probably never see it again. Anyway, try to oil lightly and repeatedly the exposed shaft with extremely light weight oil. Sewing machine grade or lighter. Don't over do it with too much oil. Give it time to work in.
Once again more isn't better.
Actually the armature that rotates is actually hollow and when new was packed with an oil soaked felt. You can't oil it. If you removed that little clip, the armature would lift off and was a replaceable part. Very pricey, and by now very hard to buy, especially that little clip from heaven.
Please don't loose those screws. irreplaceable.
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Thanks for the info. Blew out condenser and checked motor first thing. Door switches seem to be running o.k. Had that problem one time in the past and had to set tab in on freezer door. Have replaced condenser fan motor a couple of times and last one was a little less rpm's but has run o.k. for some time. When I replaced the main thermostat which capillary tube runs from top of fridge through a tube into the freezer section it was a universal type and made everything too cold so had to turn know up to warmest setting to keep fridge section from getting too cold. When box started not cooling as well I had to turn control to colder settings until I finally got to coldest setting. Then all meat went bad in freezer so I took it apart to check heater and bimetal thermostat. Freezer getting to 22 degrees empty. Is that enough or could the main thermostat be malfunctioning.
Thanks a lot jackfrost 555. I have the freezer section apart so I can see the fan has been turning when I open the door and it appears to be running fast but don't have equipment to check rpm. Freezer got down to 13 degrees but shouldn't it be getting closer to zero or lower? I will jump thermostat for 5 hours to see if it gets colder, thanks. Thermostat control is in top left of fridge with control knob. Also on top right is a cover behind which is a thermostat. There is no knob just a hex head with dot on the outer part of hex. Could this be a differential control and could it be causing it not to cool enough? I think it has cycled again now. When I got back from town freezer was at 28, now down to 23 and fridge is at 32. When freezer gets to 13 fridge is below freezing. If I would turn up the temp control to keep fridge from getting below freezing would that not raise temp in freezer which is the wrong way to go for freezer. Is that what the other thermostat behind the cover is for? So if I jump the main thermostat control for 5 hours and it gets the freezer down colder say around zero(?) then will I have to adjust the other thermostat to keep fridge warmer and freezer colder? Of course, if jumping works then I will need to replace the regular thermostat.
Thanks again. Yes there is another fan in top right of freezer compartment (actually half of it is above freezer compartment) that turns on and off with fridge door switch. Model is FPCI-19 CP VL. Couldn't find alligator clip jumper wire so will have some later today and will jump across main thermostat for 5 hrs to see if box gets colder. If it does I will replace thermostat but I will probably have to adjust the other control for damper or other fan if that is what it is to keep fridge from getting too cold. Thanks for the education and if you find out anything with the model number about the other thermostat and which way is colder or warmer I would appreciate the info. If jumping thermostat does not get freezer colder than 13 to 28 it would then look like compressor is not working right I suppose.
This morning I popped the thermostat out of its hole. Has brown wire and pink wire attached at top with screws. Also has green wire going to housing (like static ground). Checked brown and pink wires for AC voltage and got nothing. This is not DC is it?
Could defrost timer contacts not be letting current flow to thermostat? Box is running so shouldn't there be current at all times across the thermostat wires until it goes into defrost?
This morning the freezer was 25 degrees and fridge was 28. Could that other thermostat be cutting off the current and shutting down the compressor because fridge compartment too cold?
Thanks. I looked at it again and the capillary tube comes out just to the left of it and goes behind a cover that has a turned down vent. Behind the vent is an opening which must be for air to blow from freezer section to fresh food section so as you say must control fan in freezer that blows to fresh food compartment. You can turn hex head to adjust thermostat. I don't suppose that it has anything to do with freezer temp which is controlled by main tstat. Still would like to know if tstats are DC or AC as I do not get a reading when checking them on AC with voltmeter. Am trying to determine if defrost timer contacts are working to send current to tstat. If I jump wires on main tstat to check if it will get colder in freezer in five hours, won't do any good if I don't have current there.
Thanks for all your help. You were right again. I had tried turning the main tstat up in the past and box got warmer which was evidently a fluke and also that was when the defrost coil was bad and evaporator was frozen up. Anyway, I turned the main tstat up to colder setting and turned the other tstat for fresh food section fan warmer (probably 100 degrees turn) and this morning freezer is 14 and fridge is 40. This is not 8 degrees but when freezer is back together and has frozen food, etc. in it, it will probably get cooler. Looks like the tstat for fan which was set at factory (under a cover without a knob to adjust) has been set wrong 46 years and I appreciate your helping me solve problem. By the way the knob for main tstat fits other tstat so I used it to adjust with. Also I suppose on tstats that w/age the spring gets weaker and pin wears so tstat has to be turned up to compensate.
Well now I will try and find some heat resistant styrofoam to patch the pieces of insulation that the repair man left off and put it back together. I was fearful that compressor had gone bad but evidently it is o.k. since it is cooling as good as it is. THANKS A LOT AGAIN!!!
I guess freezer is not used to running as cold as it is. I began hearing a chirping sound which looks like is coming from freezer fan motor. Maybe I need to oil or give it a puff of graphite. Maybe fan motor needs to be replaced. It just makes the sound now and then - not constant.
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