Knocking sound in upper left of refrigerator.

Old model refrigerator have their defrost timer located at the back right upper corner or the left lower corner with a hole slot for a screw driver. New models have it inside the refrigerator near the thermostat control. It also has a hole slot for a screw driver.

I just changed mine yesterday and these tips listed above were unfortunately incorrect.

Step 1 - Open the passenger door
There is a panel that has no screws on the flatside of the dashboard which faces against the closed door at the jam side. Use a body tool and pry the panel carefully exposing the inside area of the glovebox. If possible dont do this in cold weather because the tabs are plastic. Inside the panel you will see one small tab that the glove box has a 1/4 plastic clip seated in the tab.

Step 2 - Open the glove box. Remove the 3 hex screws on the top interior row of the glove box.

Step 3 - At the right and left corners of the bottom of the glove box remove the two front facing screws on the lower hinge.

Step 4- At the very bottom parallel to the floor there are two more hex screws remove those (they hold the plastic vent in place underneath the glove box. Pull the vent downward to release the tabs.
IMPORTANT: Dont forget to go back to step 1 and pull the small tab from the slot in the dashboard cover area ( Inside the panel you will see one small tab that the glove box has a 1/4 plastic clip seated in the tab)

Step 5 - Pull down on the glove box to release the clips.

Step 6 - You will see a black box inside. There are three tabs (right, top, and left) pull them individually to remove the front facing cover. Inside you will see the air filter. Remove and have airflow arrow pointed downward.

Reverse steps to reinstall. Be sure to line up the clips before pressing them back in place. Do not force them!

Good luck. I hope this helps. I did mine on the first attempt with no issues in about 10 minutes (I'm not a mechanic).

You are correct this box that is in the upper left corner of the fridgerator towards the rear of the machine is actually termed as a diffuser. Its basic job is to open and close letting the cold air into the refrigerator from the freezer. When you fridgerator is to cold the diffuser, also known as the damper assembly in other units, closes and when the frigerator is to warm it opens the small fins on the door letting the cold air back into the refrigerator side of the unit. There is also a control for this diffuser located in the ceiling of your fridgerator as well. Around this time of year do to the tempreture getting hot outside I do notice more diffuser's that I have to change in a week more then diffuser controls. Is this the area that is makeing that poping sound on you? Carefully remove the diffuser not breaking either of the two thermostat lines and inspect to see if you have an ice build on the inner fins of the diffuser if you do it is best to replace the diffuser itself instead of opening it or proping something on the inside of it to keep it open. If you have any further questions message me back. And please also remember when our chat has fully concluded to rank how this opinion has helped in your appliance situation it allows me to continue helping others in similar situations in the future Thanks
Rick
p.s the part number for the diffuser is W10128734

check the electronically operated damper vent door located behind the plastic grille inside the refrige compartment in the upper left hand corner,its either a dead control,an evaporator control12 volt d.c. motor,or the motor/door shaft is broken and you need a repl

Hello,

Sounds like you have a defrost problem since the freezer side is working okay . It probably is not blowing cold air into the refrigerator side , so to check the defrost circuit , unplug the refrigerator and inside the refrigerator section at the top about 2" in from each side in the back , there are "D" slots to put a finger in , and pull downward and forward , to remove the control panel cover . Once removed , there is a 1/4" screw on each side holding the adjustment indicator panel on , 1 Phillips screw behind both light bulbs , and 1 screw holding the complete panel to the rear wall . After removing these 5 screws , at the top right corner , with about 6-8 wires going to it , is the adaptive defrost board . Sometimes you can see the electronic board and on newer refrigerator's , a white box will be seen. Inside this box , is the adaptive defrost control . Disconnect the plug going to the board and on the right side of the PLUG , the far right wire is yellow , then another color , then white . Using a small insulated wire with both ends stripped , insert one end into the yellow wire hole and the other into the white wire hole . This will bypass the adaptive board and send power directly through the defrost bimetal ( thermostat ) AND heater to check if they are good .Plug the refrigerator back in . Now , wait about 3-5 min and look for a red glow at the bottom of the inside freezer panel , which will be the defrost heater or listen for sizzling which will be the frost melting and dripping onto the heater .If NO red glow , watch for a spark while removing the jumper wire you installed , from the plug . If a spark IS seen , then the heater was on and the heater AND bimetal are good . If you see the red glow , hear the sizzling , or see the spark , then the adaptive defrost board should be replaced . If no glow , sizzling or spark , then unplug the refrigerator and reinstall the refrigerator control section .
Remove the food in the freezer section enough so that the 2 screws holding the lower freezer panel on and the freezer panel , can be removed . Remove the panel . If the heater (black element at the bottom of the coils ) wires are visible , trace then to the top of the coils and disconnect . Use an ohm meter to determine if the element is good . If the element IS good , at the top of the coils , is a 1" cylinder with 2 wires , clipped onto the coils . This is the defrost thermostat ( bimetal ) . Replace this part if the element shows good . If the element shows bad , replace the element . NOTE 1 : sometimes the element and the bimetal come wired together and the replacement part comes with a new heater and bimetal already wired together . This would be the adviseable replacement part . However , each part can still be replaced individually . NOTE 2 : If looking at the bimetal and the top plastic " cap " looks cockeyed , replace the bimetal as moisture has gotten inside and disturbed its designed function .

I hope this will helpout in solving the problem....

The flap is what open and closes to allow more or less cold air in from the freezer. There could be ice buildup inside the freezer causing this or a mechanical noise of the flap and motor running. See if you can see it from the freezer side of the vent.

check for an iced up damper vent door that wont close due to ice formation on the door that stalls the motor,you can defrost it with a hair dryer,its located between the freezer and refrigerator behind a plastic grille in the upper left corner of the refrige section

the damper vent door flap located in the upper left hand corner of the refrigerator section isn't closing due to either a bad damper door motor,frozen vent door from condensation,or the mainboard in the back is bad and is no longer controlling the door,you need to remove the plastic grille and change your temps and watch to see if the door moves when you do so

Sounds like defrost timer on back right corner has stopped in the defrost position. Located bottom left corner inside white plastic box if you are behind ref.

Here is your problem:

There are two temperature sensor wires; one should be routed around the vent on the upper left corner of the "ceiling" of the fridge. It will route inside the plastic cover in the back upper corner.
The second one is critical. It originates inside the cover and must pass through the wall of the fridge into the freezer and rest just inside a hole in the rectangle that passes through from one side to the other. If the very tip of this sensor is not well inside the freezer, the system will think the freezer is too warm, never turn off and the lovours inside the plastic housing described above will jam with ice and get stuck. This piece will have to be replaced but will continue to freeze and break until the sensors are placed in the correct locations. Don't ask me how I know all this.

Good luck.