Hello Wendi & Mike;
My name is Peter. I am a retired field service appliance technician.
If these guys in the parts store should not tell you what the problem is, otherwise they would be in the field repairing the appliances and making good money.
I am sorry you have gone through so much unnecessary expense.
You have not provided a model number which would help me solve the problem.
Anyway, The "AF" code either means Air Flow or Air Fan.
1.) Air fan:
a.) Open the dryer door. Try to rotate the dryer drum by hand. Does it move freely?
b.) With the door open. Hold the door switch in, turn on the dryer, does the drum turn? If so then your motor and fan wheel are good. Your fan wheel may be stuck with lint.
2.) Plugged up with lint:
You have a hot air distribution manifold. This often becomes plugged up especially if you have children or pets. In this case you may smell a burning odor.
3.) High temperature thermal switch and operating switch. These components are on your electric heater housing. Disconnect the wire contacts on these components. Note the color of the wires and where they go. If the two wire are the same color then it makes no difference when you reconnect them. Set your meter on Ohms for tone ring. Check these components.
Go into the following website. Put in your model number. You will get diagrams and part numbers for your dryer components. Purchase them over the internet for about 40-50% less.searspartsdirect.com
If after checking all of the above, then you have a control board problem. Don't panic! Take the control board part number on the website and search the internet. Sears wanted $265.00 for a control board. I purchase a used/remanufactured board over the internet for $40.00.
IF YOU DETERMINE IT IS THE CONTROL BOARD, GROUND YOURSELF BY TOUCHING BARE METAL BEFORE YOU TOUCH THE CONTROL BOARD. STATIC ELECTRICY WILL KNOCK OUT A CONTROL BOARD.
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