Refrigerator not cold enough- freezer OK

I have a GE top freezer model GTH21KBXACC. The freezer is very cold (-5 deg F) but the fridge is only at 40 degrees with the fridge dial set to the max setting (#7). Here are the facts:

* No ice build up behind freezer panel area, checked 3-4 different days
* Evaporator fan works fine
* Flap from freezer to fridge works fine
* Freezer is basically empty (just a bag of ice)
* I just replaced the thermostat for the fridge control

One weird thing is that with the old thermostat, the temp was 40 whether set at #4 OR #7 setting. With the NEW thermostat the #4 setting has it at 50 degrees (but I only checked it once)!

I have to get this fixed fast for my tenant ...thanks for everyone's ideas!
-Tony

 

Is there someone who has a possible idea for me to look into on this one? Thanks!

 

Well, I haven't heard anything from anyone, but I have some ideas; please help if you know them to be bad/good.

By the way, I said "condenser fan" in my original post, but I mean evaporator fan - the fan in the freezer.

I am wondering if more air flow to the fridge is needed since the freezer temp is OK but the fridge is in the mid 40's at its coldest setting. The only thing that bothers me about that theory is that the fridge thermostat should keep it running till the mid 30's are reached even if there's poor air flow. Anyone agree/disagree?

Ideas:
(1) Today I am removing the freezer adjustable flap to see if more air flow helps.

(2) If it does not, I will tape over the some of the openings in the freezer to force more air down the chute (where the flap is) as another test.

(3) I see that there is a channel in the Styrofoam that allows freezer air to channel directly to the fridge thermostat. I guess I could block that channel so super cold air doesn't directly feed onto the thermostat in the fridge and see if the temps go down.

(4) Could a slower freezer evaporator fan cause the fridge to not cool well, since it looks like the air channels deliver cold air from the freezer to the fridge? My fan seems to spin at the rate of every other freezer fan I've heard, but I will look up how to test it while I'm waiting for the temps to adjust today.

Thank you.

P.S. How does air from the freezer flow well into the fridge when there doesn't seem to be a return for the air to circulate? Maybe there is one?

 

I partially agree. The thermostat monitors the fridge temp so yes the compressor should run until the stat is satisfied but fridge may not come down to the mid 30's.

Your fridge line is available with two systems....
A mechanical fridge/freezer damper or a powered damper.
I believe your is mechanical/manual which is basic and easy to troubleshoot.

Do you feel air coming out of that damper into the fridge ?
If yes then your idea of return air could be correct. There has to be a supply area and a return area to the freezer. There may be airflow out of the damper with the fridge door open but not closed.

I don't know how the ductwork is setup on that fridge but there may be a piece of wayward insulation blocking it.

The following link is to Sears parts direct which has the best exploded views of appliances.
GE REFRIGERATOR X SERIES | Model gth21kbxacc | Sears Parts Direct

 

This is the mechanical flap type of fridge. Also, I have torn it down to its basic parts, so I DO have the parts diagram, and all the parts are accounted for. Everything related to the Styrofoam is perfect and pristine.

There is a tiny square opening that is right in front of the coiled-up thermostat tube; I wonder if this is where warm air makes its way up into the freezer? I have a photo of it:



However, I had a huge breakthrough! I wondered how could both the old t-stat and the new t-stat keep the fridge at 43 degrees? Maybe the T-stats are good but the air hitting it is too cold ...making it think the desired temp has been reached.

So I put the old one back in and moved the end of the T-stat out of its spot in front of that little square hole and more into the fridge and the 1st day it got down to 28!

But the next day it was back to 43. Maybe it was in defrost mode, So I'm going to be sampling temps over the next few days to see if there's a sweet spot where I can get the desired 35-38 degrees at the mid-point setting on the dial. I will report back.

 

OK, I moved the thermostat's coiled-up end around to different spots and it seemed to cool the fridge initially, but always seemed to go back up to the 40's. It would even freeze a little of the cup of water I had in there at first.

The only idea I had that worked was to completely block the cold air channel from the freezer which blows directly on to the thermostat. There is a square channel in the styrofoam where the evaporator fan blows freezing air directly on to the end of the thermostat. So when I blocked that channel, the fridge started to keep normal temps. This channel is exclusive to the thermostat, it's not part of the air flow system going down to the fridge. You can see the square opening in the photo above (previous post) and that it's not part of the freezer air flow to the fridge.

I got the same odd results using the original t-stat or the new t-stat!

So what changed? The 1st thing I think of is that something had to change with the cold air blowing directly on to the t-stat, but every part is accounted for; I don't see any problems.

This will be a mystery, I guess, but I did get normal temps blocking the cool air channel that's designed to blow on to the thermostat (not the other channels going to the fridge).

 

I will admit I didn't read everything so forgive me if this has been covered:

Is your evaporator clear? Not all iced up? You may have a bad evap heater/defroster. I have repaired two fridges with this same issue.

 

All the classic things to check are all good - this one's a huge mystery. I'd guess only an engineer (who designed the fridge) would be the only one to know what's going on.

 

The sensor from the thermostat can't be in the airflow from the freezer. It needs to read the actual temperature from the fridge itself.

 

P: That was my thought initially too. But this is outrightly designed to take on air flow directly from the freezer. I have another completely different fridge in my garage and it has the exact same setup. After seeing this, I just assumed that the temperature sensitivity (on/off points) were just adjusted to lower temps. I don't know; it's a mystery to me.

If you look at the photo above, you clearly see that the thermostat's long tube (which I assume is filled with mercury) is wound around a metal cylinder which is mounted directly in front of that square hole which is a direct channel of freezing air form the freezer. In the photo, I removed the winding from it's mounting and is just dangling (for experimentation).

The only thought I have is that the rest of the long tube connected to the thermostat is in the fridge area before it starts winding around the metal cylinder and it senses the AVERAGE temp of the long part still in the fridge back to the winding. So the long tube STARTS way in the front where the large dial is and runs all the way back to the channel of freezer air where the winding is.

I'd love to talk to an engineer to figure out what's going on. Thanks for the replies!!
-Tony

 

No mercury in the tube. The small part is the capillary tube. The large, bulb part, is where the temperature is sensed from.